3.06 simple message

Add basic support for SIP/SIMPLE Msgs.

To enable the feature you also need to patch the FreeSwitch code (separate Pull Request).
Then you need to add a new attribute in couchdb system_config/ecallmgr:
```
distribute_recv_message: true
```
Sorry I couldn't figure out how to issue a pull request for a single commit.
The commit you want is 	3761c09

The other 2 are not related but you might want to take a look at them.