CMS-838 Create GenerateContentNameRpcHandler and GenerateContentName API command

First create API command: GenerateContentName
which uses ContentPathNameGenerator

Then create RPC handler on path "content_generateName"
which uses the API command GenerateContentName.
Merge pull request #95 from enonic/CMS-838

CMS-838 Create GenerateContentNameRpcHandler and GenerateContentName API...