* buffer_zlib.cc, buffer_zlib.h: implement inflator.
	* Http.cc, Http.h: add support for gzip Content-Encoding.
	* Makefile.am: buffer_zlib for proto-http.
buffer.cc, buffer.h: (SetTranslator) translate unread data.
reset retries on close (already done in NetAccess though)
(IsFull) new method.
(FileCopyPeerMemory) new peer type; use IOBuffer::SetMaxBuffered and IsFull.
use FileCopy for metainfo fetching.