UI for password recovery

Part of fix for #57
Generation & storage for password recovery-keys

Part of fix for #57
Passwords can be set now using the restore link

Part of fix for #57
Sending e-mails works now

Final part of fix for #57
Cleanup ...
Use ${web.url.complete} instead of static url
Use default-mechanism to configure mail settings & Organized imports
Merge remote-tracking branch 'upstream/develop' into develop
Added lowercasing to recovery (#57) e-mail address and forced e-mail addresses in DB to be lowercase (see also #40
Removed unused constants
Merge pull request #98 from Tomok/develop

Password recovery (Issue #57)