Revert "BPMSPL-37-attachment-support: added jbpm-document module to allow attach documents to tasks"

This reverts commit 97475b2237a4e055cf48c9e9007838bfebf6f61f.
 - setting some jbpm-workitem dependencies as optional
JBPM-4328 - Unify asynchronous operations execution to utilize jbpm executor (JBPM-4329,4330)
JBPM-4328 - Unify asynchronous operations execution to utilize jbpm executor (JBPM-4329,4330) - javadocs dependency added
BZ1001906 - Two version of netty exists in kie-wb-distributions-tomcat7
Tests to verify (process/node) event history
BZ-1017327 - Deployment descriptor per deployment
JBPM-4328 - Unify asynchronous operations execution to utilize jbpm executor (JBPM-4329,4330) - enable cdi extension by default
JBPM-4334 - SQL incompatible types when using PER_PROCESS_INSTANCE strategy
JBPM-4321 - Boundary Catch Error Event does not work - throws ClassCastException
BPMSPL-37-attachment-support: improved API to upload byte[] instead of File
BPMSPL-37-attachment-support: small refactorings, renamed Service.
BPMSPL-37-attachment-support: added MarshallingStrategy