Updated src/buttons/css/buttons.css to fix Issue #191 in yui/pure

http://git.io/PbMz2g
Updated History.md in the correct format.
Added PR number (195)
Merge branch 'master' of https://github.com/achalv/pure into achalv-master

Conflicts:
	HISTORY.md
Update Buttons to use `padding: 0.5em 1em`
Merge branch 'achalv-master'