Corrected files encoding

Changed from Cp1250 to UTF-8 for better support for the Polish characters
Removed client and client adapter interfaces

The solution will be specific and bonded to one client
Created authentication tab and moved username and password fields into it
Added information about the university
Replaced BugzillaOnlineClientException with the XmlRpcException
Throw exception further

KNIME will log him by itself
Merge branch 'bugzilla_online_plugin_feature' into dev