Merge pull request #57 from rromanchuk/version-plus-plus

Bump afnetworking to 2.3.1
Remove old gem version reference in the readme.
Merge pull request #62 from markrickert/readme_update

Remove old gem version reference in the readme.
add HttpResult#status_code; fixes #64
Merge branch 'master' of https://github.com/usepropeller/afmotion