update gems and fix spec_helper
more color!
use new RSpec expect-syntax
refactor and split up runner

This allows to only run HTML or CSS stuff only
add documentation for disabling parts
use fail instead of raise
use tidy executable in $PATH if available
rescue html validator from encoding errors
fix errors if response is not array-ish
use proper url for each response processing
fix tidy path stuff
Do less querying with similar selectors
Fetch stylesheets inline, removes need for precompile
Always load the railtie, don’t rely on environment variables.

Middleware will always be present in testing, but won’t do anything unless it is enabled (currently via HEADHUNTER=true)
Add Headhunter.runner to access the runner instance