JSDK-29 Java Custom Fields. TODO: add/clean Java Docs.
Added unit test, fixed docs, copyright header cleanup.
Updated CustomData IT tests to create test directories as needed (for automation / CI)
Updated more tests to auto-cleanup appropriately after they execute.
Corrected functionality, refactored code, improved JavaDocs.
Minor method name change to ensure that the Account/Group save(Options) method reads as saveWithResponseOptions to be symmetric with the Create(Account/Group)RequestBuilder methods.
Merge branch 'account_store_mapping' into custom_data
Fixed test assertions (equals arguments were reversed)