Replace current Wiki system with Gollum Wikis.

This commit replaces the old database backed Wiki system with the
excellent Gollum git based Wiki system.

The UI has been updated to allow for utilizing the extra features
that Gollum provides. Specifically:

* Edit page now allows you to choose the content format.
* Edit page allows you to provide a commit message for the change.
* History page now shows Format, Commit Message, and Commit Hash.
* A new Git Access page has been added with the Wiki Repo URL.
* The default page has been changed to Home from Index to match
the Gollum standard.

The old Wiki model has been left in tact to provide for the
development of a migration script that will move all content stored
in the old Wiki system into new Gollum Wikis.
Add Spinach coverage for Gollum Wiki system and correct the Delete link.

The previously failing Spinach steps have been fixed with this commit.
I have also added new steps that cover the entire usage of the Wiki
system.

The new Spinach steps revealed a minor bug in the Delete page process.
The path for the "Delete this page" button was previously set to
`project_wikis_page(@project, @wiki)` when it should have been
using the singular `project_wiki_page(@project, @wiki)` path helper.

The link has been corrected and all steps are now passing.
Create Wiki migration task.

This commit adds a new Rake task for migrating all of your existing
Wiki content from your database into new Gollum repositories.

The bulk of the logic happens within the `WikiToGollumMigrator`
class which is decently test covered and located in the lib directory.

The new Rake task can be executed by running:

   `bundle exec rake gitlab:wiki:migrate`

It will output a nice log of every project that it migrates along
with success or failure messages.

I have used it on my own installation to migrate my Wikis successfully.
Use Gitlab Markdown for Markdown files and Gollum to render the rest.

This commit enables the usage of the Gitlab Markdown post processing
on all Markdown formatted files. For file types that do not contain
Markdown, it defaults to the Gollum native renderer to process the
content.
Limit available Wiki formats to Markdown and RDoc.
Fix whitespace on MARKUPS constant in GollumWiki class.
Adds DB-sensitive tablename escape for backup task.

Uses ActiveRecord::Base.connection.quote_table_name.
Fixes issue 2437.
Merge branch 'use_gollum_wikis' of https://github.com/DanKnox/gitlabhq into DanKnox-use_gollum_wikis

Conflicts:
	app/views/layouts/project_resource.html.haml
	app/views/wikis/edit.html.haml
	app/views/wikis/pages.html.haml
	app/views/wikis/show.html.haml
	spec/features/gitlab_flavored_markdown_spec.rb
few fixes afte merge gollum wiki
Merge branch 'DanKnox-use_gollum_wikis'
remove separator between search & icons in header
version up to beta1
Update gollum repository location in the Gemfile.

Github just moved the Gollum repository to it's own organization.
This commit updates the Gemfile to point to the new repo location.

I also added a specific ref pointer to a version that is known to
work well just in case they slip up and break their master branch
right at the same time someone happens to be installing or updating
Gitlab. This is about the safest we can get until they put out the
next release that resolves the Pygments dependency issue.
Update links to GitLab.com after renaming of GitLab cloud.
Merge pull request #3230 from DanKnox/update_gollum_repo_location

Update gollum repository location in the Gemfile.
Gemfile.lock with gollum
Merge pull request #3217 from chrislawlor/2437

Adds DB-sensitive tablename escape for backup task.
Show projet name with namespace on team _projects widget
Fix Wiki migration task and add more test coverage.

There was an error in the #extract_attributes_from_page method that
caused an exception when checking to see if a page named "Home"
already exists.

The check occurs to handle the renaming of the main index page to
"Home" to match the Gollum standard. If there is already a page
called "Home" then the migrator will leave that page and create
the Index page as usual. Users will need to manually rename their
old "Home" page to something else then rename their "Index" page
to "Home". Fortunately, I would be highly surprised if this case
ever comes up.

I also added more verbosity to the logging so if an error does
occur, it will be easier to track down which Wiki page is causing
the problem.
Merge pull request #3240 from DanKnox/fix_wiki_migrator

Fix Wiki migration task and add more test coverage.