Performance imprevements, cuttlefish support

Hi this PR does three things:

1) it adds cuttlefish support (http://github.com/basho/cuttelfish) in this it also changes 1 configuration option, instead of storing ip and port for graphite separately it stores it in a single configuration key.

2) It significantly improves performance, this includes dropping the key2str function and demanding binary or string keys.

3) it adds a gauge/3 function that allows specifying the timestamp to be used to write the data.