Added spring to the project
Created by: jvanbaarsen
This PR will add spring to the project
The production env. is not affected by this PR, it mostly useful for developers contributing to GitLab.
The biggest benefit is, that the spinach tests now also benefit from a pre-loader, since it was not possible to use it with spork.
Also it is not needed to start Spork when you're developing, since everything can be done true Spring
Available commands
spring rspec
spring spinach
spring rails
spring rake