Loosen restrictions on hashie gem.
Use callback in Mashify middleware.
Update gemspec for Faraday 0.9.0
Fix Proxy test for all current Faraday versions
Fix Mashify test to work with Faraday callback
Only patch Multipart-Post if neccessary, don't hardcode content-type
Merge branch 'dan/hashie' into dan/master
Merge branch 'dan/faraday-0.9' into dan/master
Remove errant "require 'pry'"
Add a link to ActiveForce on the readme.

Link to ActiveForce, a gem based on a [gist from @ejholmes](https://gist.github.com/ejholmes/5154415) that wrap Restforce in an ActiveRecord like functionality.
Merge pull request #124 from crisply/dan/faraday-0.9

Update code for Faraday 0.9
Bump version.
Merge pull request #123 from crisply/dan/hashie

Loosen restrictions on hashie gem to < 4.0
Bump version.