MessageTemplate - Change XML/BAO/DAO references from "MessageTemplates" to "MessageTemplate"
MessageTemplate - Rename XML/BAO files
MessageTemplate - Change APIv3 references from "MessageTemplates" to "MessageTemplate"
MessageTemplate - Rename APIv3 files from "MessageTemplates" to "MessageTemplate"
MessageTemplate - Update api/v3/examples
Merge pull request #1628 from totten/master-msg-tmpl-rename

Rename MessageTemplates to MessageTemplate