cleanup: convert tabs to spaces.

A few asset files had some improper white-space formatting.
misc cleanup for testing.

Minor fix to a test in `event_spec`.
[HttpUrlValidator] isolate spec from models; add descriptive comment for class.
[FilenameValidator] validate ActiveModel/ActiveRecord field values to be valid as Wayground-style filenames (with no extension).

Basically, restrict them to lower-case letters, numeric digits, underscores and dashes.
[EmailValidator] validate ActiveModel/ActiveRecord field values to be a reasonable format email addresses.
[ColourValidator] validate ActiveModel/ActiveRecord field values to be CSS colours.

(Not currently used in the main Wayground project, but used in the branch for the Calgary Democracy project. I figured it was generic enough to bring into the master branch.)
[gem] minor updates.

There's a problem with Metriknit’s use of the cane 2.6.0 gem, so forcing the 2.5 series (2.5.2, currently).
[OauthLogin] Fix Twitter OAuth logins.

Twitter changed from auth.user_info to auth.info.

Also a tiny bit of refactoring.
layout: cleanup breadcrumb display.
[Tag] default_scope to order by tag.
[ViewDouble] improve mock link_to method.

Will now work with `to_param` instead of `id` method for more accurate mimicking of the actual Rails method.

Now handles the case of a custom action specified with multiple objects in an array.

Also updated autotest’s config to map datatypes and validators.