Clarify Rails versions supported. [ci skip]
Test all but excluded methods of the FormBuilder
Add additional fields. Closes #5
Bump version.
Add coveralls
Add change log.
Add some default options, and move config.
Fix comparison of URLs and request method.

* String#casecmp returns -1/0/1, not true/false
* use request.request_method instead of request.method, which contains the
  intended method, not the physically used one (PATCH vs. POST)
* call url_for on the url, and compare with both full url and path; this fixes
  the case where a symbol or array is specified as url in signed_form_for
Add failing spec for method check.
Stylistic changes.
Add changelog entry for #6
Prefer initializing HMAC as necessary.
Bump version.
Clean up existing specs a bit.
Implement digestor class.
Add digestor to form builder.
Implement GateKeeper to authenticate form.

Including digests.
Add digestor stores.
Add an engine to render form expired view.
Add a bad digest grace period.

This is useful for minor changes that you don't want to invalidate a
form that a user is currently filling out.