Fix specs to run on rails 3.2.x

The rails 4 inputs are like:

<input data-fp-apikey=\"123filepickerapikey\" id=\"user_filepicker_url\" name=\"user[filepicker_url]\" type=\"filepicker\" />

when the rails 3.2.x are like:

<input data-fp-apikey=\"123filepickerapikey\" id=\"user_filepicker_url\" name=\"user[filepicker_url]\" size=\"30\" type=\"filepicker\" />

The difference is the size attribute. So you can no more match against a complete tag if we support both rails on specs. So change the specs to match against single attributes
Add 3.2 and 4.0 gemfiles on Travis