Spork support added

I can no longer pay attention to the fact that the test running in a project takes a lot of time. It is awful, especially if you work everything out on the virtual machine.

I think that I would be supported by a lot of people that the spork implementation will cut the time  required to load the environment.

I cannot provide the test performance for all the tests because I do not have enough patience to  wait until all the tests  pass on my machine.

```
vagrant:~/projects/my_gitlabhq spring
→ time rspec spec/models/issue_spec.rb
No DRb server is running. Running in local process instead ...
.......

Finished in 16.06 seconds
7 examples, 0 failures
Coverage report generated for Cucumber Features, RSpec, Unknown Test Framework to /home/vagrant/projects/my_gitlabhq/coverage. 2120 / 5123 LOC (41.38%) covered.

real	2m32.973s
user	0m10.385s
sys	0m3.956s
```

Run spork and:

```
vagrant:~/projects/my_gitlabhq spork
→ time rspec spec/models/issue_spec.rb
.......

Finished in 12.95 seconds
7 examples, 0 failures

real	0m16.117s
user	0m0.704s
sys	0m0.096s
```