Port functional tests to rspec
Delete unused rails performance test
Migrate VolatileLock test to rspec
Migrate redirects test to rspec
Spin out rails_helper code into support files
Migrate deduplication test to rspec
Migrate remaining integration tests to rspec
Specs: replace RSpec.describe with describe

This makes the specs more consistent
Merge pull request #175 from alphagov/port-remaining-tests-to-rspec

Port remaining tests to rspec