Cassandra (thrift API) support

I've added support for Cassandra over thrift, based on [erlang_cassandra](https://github.com/dieswaytoofast/erlang_cassandra).
One caveat, I had to explicitly copy ```cassandra_types.hrl``` to ```src/lib/cloudi_services_databases/test_ct``` because I couldn't get rebar to recognize ```include_lib```
I've also created tests for ES and Cassandra. 
```rebar ct verbose=1 suites=erlang_cassandra`` (or ```suites=erlasticsearch```).
Note that you'll need cassandra and/or ES running for the test to work...