[Android] Adds Maven Support For Gradle Dependency [xx]

Summary:
In order to easily include RN Sound in a brownfield project,
this sets up the maven dependency generation.
The maven files can then be referenced similary to how
RN is referenced in that it no longer requires adding the
native dependency to the node modules folder.

Test plan:
- verified generated maven files work as expected

Author: Thorben Primke

android/README.md

@@ -0,0 +1,15 @@
+README
+======
+
+Steps before publishing a new version to npm:
+
+1. Be sure to have the Android [SDK](https://developer.android.com/studio/index.html) and [NDK](https://developer.android.com/ndk/guides/index.html) installed
+2. Be sure to have a `local.properties` file in this folder that points to the Android SDK and NDK
+```
+ndk.dir=/Users/{username}/Library/Android/sdk/ndk-bundle
+sdk.dir=/Users/{username}/Library/Android/sdk
+```
+3. Delete the `maven` folder
+4. Run `sudo ./gradlew installArchives`
+5. Verify that latest set of generated files is in the maven folder with the correct version number
+

android/build.gradle

@@ -1,4 +1,16 @@
+buildscript {
+  repositories {
+    google()
+    jcenter()
+  }
+
+  dependencies {
+    classpath 'com.android.tools.build:gradle:3.1.4'
+  }
+}
+
 apply plugin: 'com.android.library'
+apply plugin: 'maven'
 
 def DEFAULT_COMPILE_SDK_VERSION             = 26
 def DEFAULT_BUILD_TOOLS_VERSION             = "26.0.2"
@@ -19,6 +31,86 @@ android {
   }
 }
 
+repositories {
+  google()
+  jcenter()
+  maven {
+    url "$projectDir/../node_modules/react-native/android"
+  }
+  mavenCentral()
+}
+
 dependencies {
   compileOnly 'com.facebook.react:react-native:+'
-}
+}
+
+def configureReactNativePom(def pom) {
+  def packageJson = new groovy.json.JsonSlurper().parseText(file('../package.json').text)
+
+  pom.project {
+    name "React Native Sound"
+    artifactId packageJson.name
+    version = packageJson.version
+    group = "com.zmxv.RNSound"
+    description packageJson.description
+    url packageJson.repository.baseUrl
+
+    licenses {
+      license {
+        name packageJson.license
+        url packageJson.repository.baseUrl + '/blob/master/' + packageJson.licenseFilename
+        distribution 'repo'
+      }
+    }
+
+    developers {
+      developer {
+        id 'zmxv'
+        name packageJson.author.name
+      }
+    }
+  }
+}
+
+afterEvaluate { project ->
+
+  task androidJavadoc(type: Javadoc) {
+    source = android.sourceSets.main.java.srcDirs
+    classpath += files(android.bootClasspath)
+    classpath += files(project.getConfigurations().getByName('compile').asList())
+    include '**/*.java'
+  }
+
+  task androidJavadocJar(type: Jar, dependsOn: androidJavadoc) {
+    classifier = 'javadoc'
+    from androidJavadoc.destinationDir
+  }
+
+  task androidSourcesJar(type: Jar) {
+    classifier = 'sources'
+    from android.sourceSets.main.java.srcDirs
+    include '**/*.java'
+  }
+
+  android.libraryVariants.all { variant ->
+    def name = variant.name.capitalize()
+    task "jar${name}"(type: Jar, dependsOn: variant.javaCompile) {
+      from variant.javaCompile.destinationDir
+    }
+  }
+
+  artifacts {
+    archives androidSourcesJar
+    archives androidJavadocJar
+  }
+
+  task installArchives(type: Upload) {
+    configuration = configurations.archives
+    repositories.mavenDeployer {
+      // Deploy to react-native-event-bridge/maven, ready to publish to npm
+      repository url: "file://${projectDir}/../android/maven"
+
+      configureReactNativePom pom
+    }
+  }
+}

android/maven/com/zmxv/RNSound/react-native-sound/0.10.12/react-native-sound-0.10.12-javadoc.jar

@@ -0,0 +1 @@
+60106aaefd1651dfce923a4471716e21

android/maven/com/zmxv/RNSound/react-native-sound/0.10.12/react-native-sound-0.10.12-javadoc.jar.md5

@@ -0,0 +1 @@
+dd52b4d751cec99c67422ad6a7a4eba7d8d347e6

android/maven/com/zmxv/RNSound/react-native-sound/0.10.12/react-native-sound-0.10.12-javadoc.jar.sha1

@@ -0,0 +1 @@
+1bcef3718951fc026eccd47926697f4d

android/maven/com/zmxv/RNSound/react-native-sound/0.10.12/react-native-sound-0.10.12-sources.jar

@@ -0,0 +1 @@
+2855b2257d3f4a718bd4863ca57a7cd9562091aa

android/maven/com/zmxv/RNSound/react-native-sound/0.10.12/react-native-sound-0.10.12-sources.jar.md5

@@ -0,0 +1 @@
+203e4fc952c468155bb4b9e689270736