Merge pull request #3 from alexgorbatchev/master

Adds MIT license.
0.1.0
try to inject only once, if needed...
so close but getting 'unexpected identifier' when selector has double quotes (") in it
working, with selector passed as arg, w/ s-w 2.4.2.
TODO: `all` (multi-element selector).
multi-element (`all`) finder with new approach.
take selenium-webdriver module as optional param and ensure instanceof.
tweak tests
bump version to 0.2.0