Support for array(limit, offset) as a 'limit' constructor key(Query Builder)

Hi,

This time I added support for 'limit' key working as limit (int $limit, [int $offset]) method.

I'll try to code as many points as I will be able to form my previous pull request(https://github.com/phalcon/cphalcon/pull/1205). Sorry for pushing this "one by one" but it take huge amount of time for me to get my head around C(as I'm not a C developer) so I prefer to send something before somebody else will fix/write it.

Thanks,

Kamil