Updating the code to use requests>=1.0 API

The requests library has reached 1.0 milestone and has
changed a lot of its API [1].

This commit updates the library dependency and it's
API usage

[1] http://www.kennethreitz.com/announcing-requests-v100.html
Settings a explicit minimum version for requests library
Merge pull request #76 from thulio/fixing-requests-dependency

Updating the code to use requests>=1.0 API