avatar_selection 5.x-2.0

Changes since DRUPAL-5--1-2-3:

• fixed issue reported in #126416. It was actually nothing to do with the size of the images but rather the extension, png was matched but not PNG, etc. file_scan_directory does not do case insensitive matching.
• added note to upload form about case sensitive extensions
• changes for feature request #131038 - can now only display the avatar selection for specific roles.
• fixed some stray tabs
• tidied up the settings form and avatar_selection_menu()
• removed watchdog msg for install() function and added in a warning msg if user pictures are not enabled.
• fixed bug where not all images were being removed on uninstall()
• added in message on settings form warning about disabled user pictures option and made changes for #146140
• added in patch from #146134 - "force users to select avatar" setting now requires 'access avatars' permission
• removed version line as recommended
• added in per role function
• corrected spacing, etc for coding standards
• added in changes for feature request #156957. This links to the #156954 forum post. These changes allow pagination of the avatar images and a neater way of
  selecting them. Thanks to Carlitus for these changes.
• Added in changes suggested in #132277.