Merge pull request #39 from teknico/vp

Add more error codes, messages and error checking.
Added notifications for deposit scripts
Merge pull request #40 from jimmysong/vp

Added notifications for deposit scripts
Strengthen tests by checking the correct error code is returned
Fixed according to Nicola's review comments
Merge pull request #42 from larshesel/vp

Strengthen tests by checking the correct error code is returned
Lowercased error messages, cleared up comments, shortened some lines.
No functional changes.