Add support for relative_url_root option.

This solves problem if you have set your application to be run on relative url like "/url/"
(`config.action_controller.relative_url_root` option).
Don't render layout on ApiTaster::Routes#show.

It's loaded by AJAX, so it's enough we'll load only the body of the #show response.
(this removes unneeded <script> loads and improves the speed of ApiTaster).
Add doc for ApiTaster.route_path (c3ee730d)
Change Rails version to 4.1
Fix partial rendering for Rails 4.1
Bump version
Support header injection.

Signed-off-by: Mario A Chavez <mario.chavez@gmail.com>
Support header injection.
Bump version
Fix broken js
Add global headers info to README
Exclude tags file from git
Add a note about using this gem with Rails 3.x/4.0
Fix failing tests
Set explicit sass-rails version to help travis resolve dependencies
Merge branch 'rails4'

Conflicts:
	.travis.yml
	api_taster.gemspec