Merge pull request #117 from d-Pixie/master

Allow multiple keys in call to require
Revert "Implements require with multiple parameters" -- too confusing an API.

This reverts commit 7758a3446879f27b1932eef81adb116659266218.
fix Travis link [ci skip]
Merge pull request #133 from frodsan/fix_README

fix Travis link [ci skip]
Bump version
Document how to require multiple keys in params

With reference to commit 735da78f6e570a076820cb0edd23e38c1837e5b2
Merge pull request #146 from josephers/patch-1

Document how to require multiple keys in params