Adds some basic buttons and panels for importing and exporting requirements.
Adds exporting functionality.
Changes logging from println to an actual logger.
Adds importing functionality.
Makes the import requirement button directly open the File Chooser.
Removes incorrect comments.
Fixes button icons for import and export.
Makes the export panel close on successful export.
Fixes typo in variable name.
Fixes duplication error when importing multiple times.
Fixes logger tag.
Fixes issue where requirements were duplicated.

Also ensures that this portion of the requirement was satisfied:

It will add a transaction indicating that I imported the requirement
and it will set the status to new, put it in the backlog, without a
release number, zero estimate, and no priority.
Fixes issue where clicking Export breaks the Overview.
Merge pull request #85 from Team-Combat-Wombat/dev-requirement-export

Adds importing and exporting to the requirements manager.