Return empty string if message wasn't set, instead of undefined
add test
allows "+" in email addresses, which is valid.
Merge pull request #22 from gilluminate/master

allows "+" in email addresses, which is valid.
Changed to after(errorEl) for the sake of screenreaders
Screenreaders don't automatically see DOM elements inserted before inputs
Inserting errors after the relevant input allows blind people to easily recieve these errors if the site uses happy.js
Where I learned this was: http://alistapart.com/article/designing-for-easy-interaction
added role=alert for accessibility too
Merge branch 'pr/7' into pr7

Conflicts:
	test/tests.js
Merge pull request #26 from MarnuLombard/master

Accessibilty Imporovements
Linting and lint hinting
Add happy config item

Code originally in https://github.com/HenrikJoreteg/Happy.js/pull/17
Allow config.errorTemplate. Closes #2