Improve screen projectmgr/control/EditProjectContents, to display the creation form instead of the update content (that doesn't works) when a workEffortContent is deleted. Raise by Dhiraj Gupta on issue OFBIZ-5730. Review the form to display only modification's field that can be modified.

git-svn-id: https://svn.apache.org/repos/asf/ofbiz/branches/release12.04@1643505 13f79535-47bb-0310-9956-ffa450edef68