Add support for the `data-disable` attribute.

This gives the same behavior as the `data-disable-with` attribute,
but instead of using a replacement String from the `data-disable-with`
attribute the disabled state will use the origin text/value of the element.
Tidy up `data-disable-with` test source a bit.
Merge branch 'master' into data-disable

Conflicts:
	test/public/test/data-disable.js
Trim empty newlines
Merge branch 'master' into data-disable
Update replacement logic to avoid DOM operations when we won't change the HTML after all.
Merge branch 'master' into data-disable

Conflicts:
	src/rails.js
	test/public/test/data-disable.js
Merge branch 'master' into data-disable

Conflicts:
	src/rails.js
	test/public/test/data-disable.js
Fixed helpers to use App settings helpers.
Added support for button[data-disable].