change fullurl to url and public it
added tests
added coveralls and travis-ci
added default rake task
Merge branch 'add-url-and-tests' into develop

* add-url-and-tests:
  added default rake task
  added coveralls and travis-ci
  added tests
  change fullurl to url and public it

Conflicts:
	lib/carrierwave/storage/webdav.rb
	spec/spec_helper.rb