Make things clear
Update contributing (write a PR description)
Fix typo
Parse parameters from the Accept header, and make them available into the AcceptHeader class
Don't change case for parameters values
No parameters for LanguageNegotiator
Cosmetic changes
Extract getMimeTypes() method in FormatNegotiator

+ rename sanitizePriorities() to sanitize()
split out the priority normalization logic (fixes #11)
added tests for FormatNegotiator::normalizePriorities()