Add availability to configure show_image_direct_url

This commit:
  - Add the show_image_direct_url parameter (default to false)
  - Fix spelling errors in documentation
  - Fix documentation format (use puppetdoc)
  - Add missing documentation about params

Change-Id: I8e5cb36c19ffa4ae726642a55d8fab5c6cea07b5
Co-Authored-By: Emilien Macchi <emilien.macchi@enovance.com>
Use remove_warnings from puppet-keystone

Glance client is getting the same warnings as Keystone client,
hence puppet-glance should use the same hack as puppet-keystone
until providers will be refactored to use API calls instead.

See https://bugzilla.redhat.com/show_bug.cgi?id=1043725 for more details

Change-Id: I99e4308d0731307c019ad6cab8db5feee1b0ed73
Merge "Use remove_warnings from puppet-keystone"