JRuby compatibility.
rest_client gem version fixed.
Removed curb dependencies.
rest_client gem version fixed.
Merge branch 'master' of github.com:kojnapp/bitstamp into jruby-compatibility

Conflicts:
	spec/fixtures/vcr_cassettes/bitstamp/order_book.yml
Merge pull request #18 from MGalv/jruby-compatibility

Jruby compatibility