First try for #108
Note that I've not updated the test case and there are tests that are going to fail.
In addition, I've only tested from CSV to ABOUT file. I've not tested the rest.
Fix and update test cases
Commit code update for #108

It's now able to log custom fields from ABOUT file to CSV.

ToDo: write and update test cases
update test cases
Fixed #108 - Added test case for function "get_custom_field_keys()"
Handle cases where keys in  the mapping list contains spaces.
Merge branch '108_options_to_include_non_supported_keys' into develop

Conflicts:
	about_code_tool/tests/test_about.py
	about_code_tool/tests/test_genabout.py

Fixed all the test cases conflicts