Feature/bulk wf manager

Implementation of Issue #247

WDYT?

If there arent any significant cocnerns - I can see about writing some unit tests though that may be tricky due to how this is works.

![bulk_workflow_manager__acs_aem_commons](https://cloud.githubusercontent.com/assets/1451868/3563497/87f7cedc-0a3a-11e4-9dc1-cf94eabaa839.png)

![bulk_workflow_manager__acs_aem_commons](https://cloud.githubusercontent.com/assets/1451868/3563502/c8fecd36-0a3a-11e4-98c3-5aba449c96f8.png)

![bulk_workflow_manager__acs_aem_commons](https://cloud.githubusercontent.com/assets/1451868/3563503/d5083e1e-0a3a-11e4-9728-50fd7ac0537c.png)

![bulk_workflow_manager__acs_aem_commons](https://cloud.githubusercontent.com/assets/1451868/3563509/1fc95b68-0a3b-11e4-9007-cf8f13f124c2.png)

@bstopp yeah; i think even though most of the commands are very short this is the cleaner way to go. Ill look to breaking into separate servlets; Sling selector resolution effectively takes care of the command pattern impl.