New LDP charter draft

Hi everyone,

I had a (late) first pass at the new LDP charter [0]. There are several
things we need to discuss, that I've marked with either TBD or @@TODO.
Arnaud suggested we start the discussion on the mailing list, to save
time during the next call.

So..I guess I'll go first: I removed *authentication* from the ACL item,
since I don't think it was supposed to be there in the first place.
Would people consider authentication to be in scope?

-- Andrei

[0] https://www.w3.org/2012/ldp/wiki/LDPNext2015_Charter