Update version for 0.5.0 release (#158)

* Setting version to 0.5.0

* Setting version to 0.5.1-SNAPSHOT

* Update README.md

Author: lu-wang-dl

README.md

@@ -54,7 +54,7 @@ Additionally, for developement, you need the following dependencies:
 Assuming that `SPARK_HOME` is set, you can use PySpark like any other Spark package.
 
 ```bash
-$SPARK_HOME/bin/pyspark --packages databricks:tensorframes:0.4.0-s_2.11
+$SPARK_HOME/bin/pyspark --packages databricks:tensorframes:0.5.0-s_2.11
 ```
 
 Here is a small program that uses TensorFlow to add 3 to an existing column.
@@ -151,7 +151,7 @@ The scala support is a bit more limited than python. In scala, operations can be
 You simply use the published package:
 
 ```bash
-$SPARK_HOME/bin/spark-shell --packages databricks:tensorframes:0.4.0-s_2.11
+$SPARK_HOME/bin/spark-shell --packages databricks:tensorframes:0.5.0-s_2.11
 ```
 
 Here is the same program as before:
@@ -204,14 +204,14 @@ build/sbt distribution/spDist
 Assuming that SPARK_HOME is set and that you are in the root directory of the project:
 
 ```bash
-$SPARK_HOME/bin/spark-shell --jars $PWD/target/testing/scala-2.11/tensorframes-assembly-0.4.1-SNAPSHOT.jar
+$SPARK_HOME/bin/spark-shell --jars $PWD/target/testing/scala-2.11/tensorframes-assembly-0.5.1-SNAPSHOT.jar
 ```
 
 If you want to run the python version:
 
 ```bash
-PYTHONPATH=$PWD/target/testing/scala-2.11/tensorframes-assembly-0.4.1-SNAPSHOT.jar \
-$SPARK_HOME/bin/pyspark --jars $PWD/target/testing/scala-2.11/tensorframes-assembly-0.4.1-SNAPSHOT.jar
+PYTHONPATH=$PWD/target/testing/scala-2.11/tensorframes-assembly-0.5.1-SNAPSHOT.jar \
+$SPARK_HOME/bin/pyspark --jars $PWD/target/testing/scala-2.11/tensorframes-assembly-0.5.1-SNAPSHOT.jar
 ```
 
 ## Acknowledgements

version.sbt

@@ -1 +1 @@
-version in ThisBuild := "0.4.1-SNAPSHOT"
+version in ThisBuild := "0.5.1-SNAPSHOT"