Added rvm files
Fix Rakefile to use Rspec
Uses environment variables instead of bit_stamp_details.yml on specs
Refactory spec_helper
Implements VCR to speed up specs and avoid lots of hits on production service
read_bitstamp_yaml => setup_bitstamp
MissingConfigExecption => MissingConfigExeception
Implements new API authentication
Updates README to follow last modifications
Version bump to 0.3.0
Regenerate gemspec for version 0.3.0