AI-5527 - Enable multithreaded rspec testing
Each fixture installation will be assigned to one 8 processes. Each _spec.rb file will be assigned to one of 8 processes
Comparing the puppet5 test for cerncollectd_contrib time went down from 8m30 to 2m30.
There is a new file ci/boilerplate/.rspec_parallel
which is advised to be copied to the code directory.