Issue 290. MkPublicKey.patch() method implemented.

In this pull request I want you to review and merge to 'master' following changes:
1. MkPublicKey.patch() method implemented
2. MkPublicKeyTest.canBePatched() test implemented and ignore annotation removed.
3. MkPublicKeyTest.canRetrieveAsJson ignore annotation removed(sorry but I forgot it in my previous task)
4. Some Java-docs changes in MkPublicKeyTest.