Fast ruby idioms

[michaelachrisco]

The fasterer gem has some good examples showing what methods are currently faster within ruby. I ran it on grape and found a few areas of improvement.

$ fasterer
lib/grape/dsl/inside_route.rb
Parallel assignment is slower than sequential assignment. Occurred at lines: 225.

lib/grape/endpoint.rb
Hash#fetch with second argument is slower than Hash#fetch with block. Occurred at lines: 155.

lib/grape/middleware/formatter.rb
Parallel assignment is slower than sequential assignment. Occurred at lines: 20.

lib/grape/middleware/versioner/header.rb
Parallel assignment is slower than sequential assignment. Occurred at lines: 47, 122, 129.

spec/grape/integration/rack_spec.rb
Parallel assignment is slower than sequential assignment. Occurred at lines: 23.

spec/grape/middleware/formatter_spec.rb
Parallel assignment is slower than sequential assignment. Occurred at lines: 12, 143, 147, 151, 157, 167, 172, 177.

spec/grape/middleware/versioner/accept_version_header_spec.rb
Parallel assignment is slower than sequential assignment. Occurred at lines: 21, 27.

spec/grape/middleware/versioner/header_spec.rb
Parallel assignment is slower than sequential assignment. Occurred at lines: 18, 25, 32, 41, 47, 59, 65, 75, 81, 102, 108, 131, 137.

[michaelachrisco]

Ill add in a quick PR.

[michaelachrisco]

I believe we can exclude the Parallel assignment is slower than sequential assignment. error statements as fastruby/fast-ruby#50 (comment) shows the exact opposite recomendation from fast ruby.