Changable cookie names and values

hi again,

not the most handy PR (seeing as I made to functional tweak on top of a refactor of the code I did, namely: https://github.com/weare2ndfloor/cookieCuttr/pull/11).

the idea behind making the cookie name settable via an option is twofold:

+ makes it easy to use acceptance cookies on different site sections and or subdomains 
+ allows cookie acceptance to be forcibly reset (possibly desired/required as part of a policy change) even when someone has previously accepted cookies

... granted making the cookie value settable is a bit bogus but it might allow someone to save a few bytes :)