Prepare version 0.5.26
Prepare version v0.5.25
Move rspec integration endpoint into mutant/integration/rspec
Allow failures on 2.1.2
Prepare v0.5.22
Prepare v0.5.21
Prepare version 0.5.20
Prepare version 0.5.19
Prepare v0.5.18
Prepare version 0.5.17