Merge pull request #15 from emsa23/master

Towards 2.6
[maven-release-plugin] prepare release PrioritySorter-2.6
[maven-release-plugin] prepare for next development iteration
Refactored JobGroup to make it more dynamic

 * Replaced the view and jobFilter options in the 
   JobGroup with Descriptable JobInclusionStrategy.
 * Implemented the view with jobFilter options in
   ViewBasedJobInclusionStrategy
 * Added AllJobsJobInclusionStrategy
[JENKINS-21337] Add support for cloudbees-folders

Added CloudbeedFoldersBasedInclusionStrategy to enable
JobGroup creation based on a Folder.