Refactored a bit to correct style

Style following: https://github.com/bbatsov/ruby-style-guide
also test against ruby 2.0.0
remove whitespace from Gemfile
add ClientMiddleware
Prepare middleware for Sidekiq 3 upgrade
fix metrics not reporting on client submit
fix variable not found and missing result return
whitespace fixes
fixed tests
Merge pull request #6 from Jimdo/client_metrics

Client metrics