Add ability to disable endpoint configuration

It is possible to disable endpoint configuration by setting
the value of the configure_endpoint and configure_s3_endpoint
parameters to false.

The default value is true, preserving default behavior.

Change-Id: I0f9afb78c181573a30f93dc4f862f86baa3efe31
Closes-bug: #1279071

Conflicts:
	manifests/keystone/auth.pp
	spec/classes/swift_keystone_auth_spec.rb