Closes #80

Fixes an NPE when deploying a process from the modeler.
Added identitylinks to process-definitions in REST (candidate starter)
Added identitylinks to process-instance REST
Added shorthand to get procDef resource without resourceId in REST
Exposing BPMNModel through REST
More implementation of history REST API
Merge branch 'master' of https://github.com/Activiti/Activiti
ACT-1696: javadoc for activiti-ldap
ACT-1696: user guide docs for activiti ldap. Still needs review + section on maven.
Merge branch 'master' of github.com:Activiti/Activiti
ACT-1696: finished user guide for activiti-ldap
fix for ACT-1685 and ACT-1679
Merge branch 'master' of https://github.com/Activiti/Activiti
Fix for ACT-1680
Relative Due Date
http://forums.activiti.org/content/time-duration-support-user-task-due-date
Fix for ACT-1702
Fix for ACT-1703
Merge pull request #84 from balsarori/actmaster

Relative Due Date for User Task
Altered docs according to pull request #84
Added process definition category update to REST