#JC-1869:Questions permissions:
*Rewrote PluginsPermission factory. Now it not caches plugin permissions. It always returns actual state.
 *Interface PluginWithPermissions renamed into PluginWithBranchPermissions because, I think, there is no sense to have so common interface in current step (If plugin will work with all 3 kinds of permissions may sense to split it into separate plugins).
*Removed handling general and profile permissions for plugin to prevent premature complication
*Corrected NullPermission enum: removed unused properties
#JC-1869:Questions permissions:
*Corrected all pom.xml files. Now there is correct indentations in them
 *All pom.xml files now use ${project.gtoupId} instead of org.jtalks.jcommune
#JC-1869:Questions permissions:
*Unit tests added
*PluginManager renamed into PluginPermissionManager
#JC-1869:Questions permissions:
*Added documentation
Merge branch 'master' of github.com:jtalks-org/jcommune

Conflicts:
	jcommune-plugins/questions-n-answers-plugin/src/main/java/org/jtalks/jcommune/plugin/questionsandanswers/QuestionsAndAnswersPlugin.java