Merge pull request #6 from michalbe/master-temp

[FILEBIT-CLIENT] - callback fix
Merge pull request #7 from michalbe/master-temp

[FILEBIT-CLIENT] - cleaning
Merge pull request #8 from michalbe/master-temp

[FILEBIT-CLIENT] - error handling
Merge pull request #9 from michalbe/master-temp

[FILEBIT-CLIENT] - errors in callbacks
Merge pull request #10 from michalbe/master-temp

[FILEBIT-CLIENT] - lint fixes
[FILEBIT-CLIENT] - :octopus: proper error handling