Add CSV import strategy

[mfl28]

• Adds CSV tensorflow format as supported annotation import format.
• Switches from Opencsv to Jackson CSV databind as the former weirdly capitalizes the field-names (with no simple option to turn this off).
• Adds unit tests.

Closes #146 .

[codecov]

Codecov Report

Attention: Patch coverage is 90.43478% with 11 lines in your changes missing coverage. Please review.

Project coverage is 86.49%. Comparing base (b8d0c1c) to head (fcb5bcc).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
...28/boundingboxeditor/model/io/CSVLoadStrategy.java	80.00%	9 Missing and 2 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #147      +/-   ##
============================================
+ Coverage     86.47%   86.49%   +0.01%     
+ Complexity     1499     1494       -5     
============================================
  Files            97       99       +2     
  Lines          5991     6021      +30     
  Branches        549      535      -14     
============================================
+ Hits           5181     5208      +27     
- Misses          532      535       +3     
  Partials        278      278              

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