Merge pull request #3 from weed0r23/features/citeq

[FEATURE] Add HTML message rendering for stage change notifications
[TASK] Raise version to 0.6.1-dev
[TASK] Hook to post-process version count result

Requires https://forge.typo3.org/issues/61725 of TYPO3 CMS 7
[TASK] Enable version count post-processing by configuration only
[FEATURE] content dependant notification e-mail subject

The subject of the notification E-mail contains now information about the touched main nodes, the backenduser and the stage.

The main node is the first node of the touched rootline. In some cases it might be helpful to exclude some nodes. This can be configured by adding a comma separated list of nodes in the notificationSubjectExcludedNodes property