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)

I think i would fall back on the SRP. One servlet per function is more appropriate than one that handles all the different commands. OR you can have one servlet for all commands, but use the Command Pattern to manage the SRP rules; and an interface for executing defining the command API, and then an implementation per command.