[FIXED JENKINS-15753] Allow spaces in group names.
Remove not existed @param.
Add version and add dependency intact it will exclude potential problems with lost dependency and "class not found" exceptions on current jenkins
Fix slf4j version missmatch by using newly rest-api library.
Ignore .idea config files.
Merge pull request #5 from KostyaSha/for-merge

Portion of fixes
Allowing blank group to specify no group restrictions
Update src/main/resources/de/theit/jenkins/crowd/ErrorMessages.properties

Group is no longer mandatory
Update src/main/resources/de/theit/jenkins/crowd/ErrorMessages_de.properties

Group is no longer required
Clean-up code after cherry-picking optional functionality for group restriction.
Don't suppress compiler warnings.
Fix log messages by simplifying type.
Don't restrict groups.
More SSO optional parts.
Fix doc description.