Merge pull request #26 from jamesbrink/misc_fixes

Refactored Hashes and Arrays to close #25
This resolves an exception for 'Rack::Lint::LintError: header key must be a string, was Symbol'
Merge pull request #27 from jamesbrink/fix_rack_lint_exception

Fix Rack::Lint exception
[Closes #34] Update gemfile.lock
Merge pull request #35 from jamesbrink/gem_updates

[Closes #34] Update gemfile.lock
Updated Docker container to use unicorn.
Removed USER barcoded to work around issues caused by index.docker.io builds
Updated Docker container to Ubuntu 14.04 and Ruby to 2.1.2
Added support to cach invalid data on POST