New mavlink_ftp unit test data
Added mavlink_ftp unit test
New mavlink_ftp unit test
Improved unit test framework

- Added init/cleanup calls before after test
- Added ut_compare macro with better failure reporting
Generator for mavlink_ftp test files
Tweak for mavlink_ftp api change
Additional FTP command support plus unit test

- Restructured to a flatter class implementation
- Added support for create/remove directory, remove file
- Refactored error codes and command opcodes
- Added unit test support
- Fixed bugs found by unit test
Merge pull request #1345 from DonLakeFlyer/FTP

More FTP work