SSL support for client-server communication using Thrift SSL socket.

This is the change which providescapability for a php client to communicate to a Cassandra server over SSL, by setting certain SSL properties in PDO constructor in the php code. Check changes in tests/config.inc-dist for more information.

Same test suit was used to test this implementation, by just one minor modification in all tests i.e. by adding "params" parameter to PDO constructor and then for SSL based tests, adding new properties to the params array.

All tests with the implementation pass if Cassandra server is configured correctly with key/cert in keystore/truststore. Please refer to wikipage-edit.txt for more details.

Note: If the changes don't compile with Thrift 0.9.1, try using next release version 0.9.2.