XD-245: Added basic job support
* Adds a new jobs directory under modules
* Allows DSL users to specify a job via the DSL
* Configuring a job via the DSL registers one that has the XML stored in the modules/job directory
* When a job is registered, it is immediately executed (need to remove this once we have a trigger concept in place).
XD-245 - Polishing

* Add `modules/job` folder
* Add README to `modules/job`
* Add `package-info.java` to `org.springframework.xd.dirt.plugins.job`
* Add missing ASL license header
* Add @since tags
Merge pull request #78 from mminella/XD-245

* mminella-XD-245:
  XD-245 - Polishing
  XD-245: Added basic job support * Adds a new jobs directory under modules * Allows DSL users to specify a job via the DSL * Configuring a job via the DSL registers one that has the XML stored in the modules/job directory * When a job is registered, it is immediately executed (need to remove this once we have a trigger concept in place).