This commit alters views for the following models to use the markdown cache if
present:
* AbuseReport
* Appearance
* ApplicationSetting
* BroadcastMessage
* Group
* Issue
* Label
* MergeRequest
* Milestone
* Project
At the same time, calls to `escape_once` have been moved into the `single_line`
Banzai pipeline, so they can't be missed out by accident and the work is done
at save, rather than render, time.
I decided to create a fork of rouge as rouge lacks a HTML formatter with
the required options such as wrapping a line with <span> tags.
Furthermore I was not really convinced about the clarity of rouge's
source code.
Rugments 1.0.0beta3 for now only includes some basic linting and a new
HTML formatter. Everything else should behave the same.
