idempotent as middleware
move idempotent/instrumentor rescue stuff into error_call
move uri parsing to Excon.new
allow for user configurable uri parser
move VALID_CONNECTION_KEYS to Constants
move idempotent test to middleware directory
fixed bug where generated exceptions contained a hash rather than a Excon::Response object
Merge pull request #200 from krames/response_fix

Fixed issue with Expects middleware
Release 0.19.0
move response parsing back to response, facilitates reading ssl proxy connect response
Release 0.19.1