Added support for optional GID when leaving a group
Fixed syntax
fix wrong way of getting args in DELETE method
fix missing cast
fix old typo preventing the master to be reset if the DJ manages to join another group (leaveGroup servercomm didn't work).
small refactoring and adding comments
Changed name of autogroup
fix typo preventing leaveGroup function to work properly, nobody was leaving his group from the server point of view
Merge branch 'groupSuggestion' of https://github.com/lca4/unison-recsys into groupSuggestion
fix typo: forgot to cast a string to unicode
Merge branch 'groupSuggestion'
Merge branch 'dev/solo'
Error handling improvements

* Error messages
Adds log messages in case of errors, updates exception messages

* Error handling
New OPERATION_FAILED error type, to be used for e.g. if a copy/remove operation
fails.
Adds non-emptiness checks, raises exception in case of emptiness.