Clarify ShorthandLinter spec structure
Clarify ShorthandLinter spec structure

- Group example groups by whether they pertain to full rules or to a
  single property.
- Tidy example group names.

Related Story:
  http://www.pivotaltracker.com/story/show/43148129
  ("Teach scss-lint about missed shorthand case")

Change-Id: Iabb4d75cf9aaf8e8a85c66b1ccdd5a530afc2f68
Reviewed-on: https://gerrit.causes.com/17748
Reviewed-by: Alex Wallace <461c07effd15f00b2944fe6dc80cb9421a61a570@causes.com>
Tested-by: Joe Lencioni <1dd72cf724deaab5db236f616560fc7067b734e1@causes.com>

ingdir/scss-lint,gatero/scss-lint,leseulsteve/scss-lint,davecarter/scss-lint,ivantsepp/scss-lint,bkeepers/scss-lint,teoljungberg/scss-lint,golmansax/scss-lint,gajus/scss-lint,chatzipan/scss-lint,cih/scss-lint,baileyparker/scss-lint,dwayhs/scss-lint,philipgiuliani/scss-lint