added support for CMIS extension: content stream hash 

git-svn-id: https://svn.apache.org/repos/asf/chemistry/opencmis/trunk@1580826 13f79535-47bb-0310-9956-ffa450edef68
CMIS-770: minor content hash implementation corrections

git-svn-id: https://svn.apache.org/repos/asf/chemistry/opencmis/trunk@1580847 13f79535-47bb-0310-9956-ffa450edef68
Merge remote-tracking branch 'upstream/trunk' into trunk
https://issues.apache.org/jira/browse/CMIS-771