specs a bit refactored & updated to support 1.9.3 as well as 1.8.7

specs were failing for me on 1.9.3 because of FSPath and nitems() usage. Have refactored it not to use the 2 dependencies.

Added Gemfile so we can just 'bundle' to install dependencies.

All but audio tests are passing on 1.9.3 and 1.8.7.

Audio tests are throwing: function ph_readaudio not found [libpHash.so] but I suspect my installation of pHash being not complete (stock Ubuntu 12.10 universe).

On JRuby, also text similarity tests are failing (undefined method 'free' for FFI::Pointer) but I intend to fix it another time.