Extending Runners API to include GET /runners call

  * The GET /runners call retrieves a list of all runners registered
    on the Gitlab CI instance.

Extending API to manipulate Projects and Runners

  * Fixed several deprecation warnings

  * Removed webmock in favor of running integration tests against
    demo.gitlab.com

  * Made :per_page and :page on Project.from_gitlab optional for API
    calls

  * Added call to retrieve Gitlab CI projects that are not only
    authorized, but "owned"

  * The following actions are now supported:

    GET /projects/:id - returns information about a project
    GET /projects - returns list of all projects
    PUT /projects/:id - updates project information (see docs for more info)
    DELETE /projects/:id - removes a project
    POST /projects/:id/runners/:runner_id - links a project to a runner
    DELETE /projects/:id/runners/:runner_id - removes link between project and runner

projects api