Merge pull request #11 from mogetutu/master

Code documentation quick spellcheck (see #10)
Simplify README (issue #12)
Change gem homepage
Ignore _site folder generated in gh_pages branch
Update development dependencies
Bump up version & update CHANGELOG

* This is in preparation to deploy to rubygems.org … but we should do
this only after tests all passed (since I moved files around I might
have broken stuff)
Safer if we stick to the GitHub URL
Fix error on Traivs-CI due to old bundler
Bundler not playing nice with Travis-CI
Set up Coveralls
Incorrectly set to use pro service
Fix typo
Link to the link rot proof URL
Single quotes
Fix url to license
Update copyright year

See
http://programmers.stackexchange.com/questions/210472/is-renewal-of-mit-
license-needed-on-github-at-the-beginning-of-each-year
Reorganise gitignore file
Ignore coveralls file generated while running test
Write generate_order_url method tests
Install web mock and upgrade bundler