fix regex check for wrt app id in msg handler

change regex to make the BID or IID prefix optional. should fix message
storm due to looping messages that cannot be delivered.

Jira-issue: WP-1264
Merge pull request #60 from aldafu/WP-1264-fix-regex-for-wrt-app-id-in-msghandler

fix regex check for wrt app id in msg handler