Clarifies where to find the releases

Resolves issue #644
Merge pull request #645 from spuder/patch-1

Clarifies where to find the releases
Add Ruby 2.1.2 to the README
Merge pull request #656 from adamnbowen/patch-2

Add Ruby 2.1.2 to the README
Typo
Merge pull request #658 from gfestari/typo

Typo
Merge remote-tracking branch 'upstream/master'