Use Ruby 2.1.2

Hoping this will speed up data-anonymization.
Merge pull request #247 from alphagov/feature/newer-rubbies

Use Ruby 2.1.2
Don’t install development gems in CI

debugger doesn’t work under 2.1.2 and isn’t needed.
Update whenever and chronic

http://stackoverflow.com/questions/14880347/whenever-gem-is-throwing-cant-iterate-from-time-error
Don't build on 1.9.3 in travis

We run 2.1.2 in production now.
Reduce number of workers

Want to use some of the RAM on our production environment for a RAM disk
to make il2->il0 data run faster.
Remove debugger gem.
Display the Phase's financial year alongside its name.