Match on the highest version number instead of direct equality checking

This commit fixes #36 as well as a few underlying issues thereof. Operating
systems define their "named" platforms differently. For example, Ubuntu defines
an OS release as X.Y (like Ubuntu 10.04 -> "precise"), whereas Debian defines
an OS release as X (like Debian 7 -> "wheezy"). Prior to this commit, a new
release of Debian (like 7.1) would fail to match on the +debian_wheezy?+
matcher.
Add Object#blank as a core extension
Only define core extensions if they do not already exist
Add String#flush core extension
Fix string %Q literals
Remove stove
Release v1.3.0
Bump version in recipe
Update date on Changelog
fixing a few spelling errors in README.md
Merge pull request #39 from jrwesolo/readme_spell_fix

fixing a few spelling errors in README.md
Fixed unit test for '#installed?'