[UIMA-3072] add phase for descriptor mojo, and set skiperror flag for no annotations found to let helpmojo create the java code.
[UIMA-3072] add phase for descriptor mojo, and set skiperror flag for no annotations found to let helpmojo create the java code.

git-svn-id: 71fdd81d427d1664ceef220cd41fb697a2614719@1502261 13f79535-47bb-0310-9956-ffa450edef68

apache/uima-build,apache/uima-build,apache/uima-build