Closes #3311

Closes https://github.com/gitlabhq/gitlabhq/issues/8763

In order to be consistent with !1490 doing it for the web interface

This ensures that blocks defines using "benchmark_subject" have access
to methods defined using let/subject & friends.

This class method can be used in "describe" blocks to specify the
subject of a benchmark. This lets you write:

    benchmark_subject { Foo }

instead of:

    benchmark_subject { -> { Foo } }

This benchmark suite uses benchmark-ips
(https://github.com/evanphx/benchmark-ips) behind the scenes. Specs can
be turned into benchmark specs by setting "benchmark" to "true" in the
top-level describe block like so:

    describe SomeClass, benchmark: true do

    end

Writing benchmarks can be done using custom RSpec matchers, for example:

    describe MaruTheCat, benchmark: true do
      describe '#jump_in_box' do
        it 'should run 1000 iterations per second' do
          maru = described_class.new

          expect { maru.jump_in_box }.to iterate_per_second(1000)
        end
      end
    end

By default the "iterate_per_second" expectation requires a standard
deviation under 30% (this is just an arbitrary default for now). You can
change this by chaining "with_maximum_stddev" on the expectation:

    expect { maru.jump_in_box }.to iterate_per_second(1000)
      .with_maximum_stddev(10)

This will change the expectation to require a maximum deviation of 10%.

Alternatively you can use the it block style to write specs:

    describe MaruTheCat, benchmark: true do
      describe '#jump_in_box' do
        subject { -> { described_class.new } }

        it { is_expected.to iterate_per_second(1000) }
      end
    end

Because "iterate_per_second" operates on a block, opposed to a static
value, the "subject" method must return a Proc. This looks a bit goofy
but I have been unable to find a nice way around this.

If this directory were to be empty this would result in warnings being
printed to STDERR, cluttering spec output. Doing this in Ruby fixes this
problem (and also removes the need for shell alltogether).

Also adds the ability to run rspecs with relative_url_defined on the enviornment. For example:

RELATIVE_URL_ROOT=/gitlab rspec

Closes #1728

- Memoize variables a bit more cleanly
- Add user to project's team

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

This reverts commit 5daf44b7, reversing
changes made to 2f706fbd.

This reverts commit 957e849f, reversing
changes made to 6b9dbe9f.
Signed-off-by: NDmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Encapsulates the logic for `Gitlab::Access::WHATEVER` levels.

Prior, CI seemed to be freezing after running these specs.