Safely encode reserved parameters in query string

Fixes #76

There's a lot of confusion about this, the default implementation of
URI.escape is marked as "obsolete", CGI.escape does another work, a safe
solution seems to use https://github.com/sporkmonger/addressable without
adding a new dependecy I found that encode all not unreserved characters
(unfortunately that doesn't mean all reserved characters) it's a pretty
safe solution, see http://tools.ietf.org/html/rfc3986#section-2.3