Move some request functionality into a more generic scope.

Can we move some of the functionality of the Request class into its own?
This would cut down on the complexity of the main class (having 1240 lines even after this change).

Alternative for class name right now: "Language"

Easy move:
- parseAcceptWithQualifier()
- acceptLanguage()

Not so easy (and maybe not necessary/possible) due to some non static env() access:
- clientIp()
- referer() (optional)