Add mysql-proxy to enable read-only access to a db

This commit adds a mysql_proxy module which will setup a read-only
proxy to a mysql db. This also configures a proxy to the subunit2sql
db to run on logstash.o.o to provide read only access to the data in
the database.

Change-Id: I478baca354354347fe50074a8e3b9f66ca890d55
Merge "Add mysql-proxy to enable read-only access to a db"