`User#starred_projects` doesn't perform any visibility checks. This has
a couple of problems:

1. It assumes a user can always view all of their starred projects in
   perpetuity (project not changed to private, access revoked, etc.).
2. It assumes that we'll only ever allow a user to star a project they
   can view. This is currently the case, but bugs happen.

Add `User#viewable_starred_projects` to filter the starred projects by
those the user either has explicit access to, or are public or
internal. Then use that in all places where we list the user's starred
projects.

Also the specs have a minor improvement. Mainly the access right spec.
Changes are reflected in the docs

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Attempting to use the /projects/:id API by specifying :id in
"namespace/project" format would always result in a 404 if the namespace
contained a dot.

The reason? From http://guides.rubyonrails.org/routing.html#specifying-constraints:

"By default the :id parameter doesn't accept dots - this is because the dot is
used as a separator for formatted routes. If you need to use a dot within an
:id add a constraint which overrides this - for example id: /[^\/]+/ allows
anything except a slash."

Closes https://github.com/gitlabhq/gitlabhq/issues/9573

This standardizes all the project API formats. Also needed to support Huboard.

Fixes #4112

Closes #3864

- Enable CI by default for all new projects

Changed the authentication method for removing fork through API
Reflected changes to new auth method in API specs

This was previously possible through the API but can now be done
through the project#edit settings screen if the current user is
the owner of the project.
Update changelog

Also updated example request url

Added changelog item

Allow admins to use restricted visibility levels when creating or
updating projects.

Changed from using cases to set the sort variable, to use a one line if/else statement

Added support for order_by and sort parameters, to sort the projects by the specified values.
Updated projects api documentation including the order_by and sort parameters

Always delete repositories from the filesystem when deleting a project.

Update the project API controller to use `Projects::DestroyService`
instead of calling `Project#destroy` directly.

Also add an optional parameter, `:keep_repo`, that allows a project to
be deleted without deleting the repository, wiki, and satellite from
disk.

This change adds POST /projects/fork/:id to the API for forking
a project into the namespace of the authenticated user, like the
"create fork" link in the GUI does. It also calls the same code.

Failure and permission checks (except for conflict) are already
implemented and handled in ForkService and the API, so the added
code is simple and does not alter anything.