Fix Makefile to use system-wide rebar
This is an Erlang NIF for Google's snappy fast compressor and decompressor.
Google snappy's official repository and bug tracking system is at:
Its source is included in this project.
https://github.com/fdmanana/snappy-erlang-nif
Snappy is much faster than zlib's deflate compression, specially for reasonably large amounts of data. Here follow a few basic tests.