[New Feature][Issue-40] Adds Processing Indicator gif to images
[New Feature][Issue-40] Adds utility classes for hidden and invisible
[New Feature][Issue-40] Adds re-processing-indicator to _buttons.scss

Added here rather than in forms since the positioning of the throbber needs tweaking in the btn-group, and generally shows up there more than anywhere else.
[New Feature][Issue-40] Adds button group and button group submitting example to form.html screenshot
[New Feature][Processing Indicator] Changes references to the CI builds for Canon CSS and JS to local files
[New Feature][Processing Indicator] Adds information about button groups to buttons post
[New Feature][Processing Indicator] Adds "create-form" id for cross-linking to subsection divider on forms post
[New Feature][Processing Indicator] Modifies rs-processing indicator

-Increases margin-top for processing indicators in an rs-btn-group
-sets correct width and height via the icon mixing
Merge pull request #66 from rackerlabs/add-processing-throbber

Add processing throbber