StreamingFetcher is now just Fetcher, and its FetchStreaming is now
just Fetch.
SeekFetcher is gone. Blobs are max 16 MB anyway, so we can slurp to
memory when needed. The main thing that cared about SeekFetcher
was the GET handler, ServeBlobref, because http.ServeContent needed
one for range requests. That's rewritten in an earlier commit, using
the FakeSeeker from another earlier commit.
Lot of code got simpler as a result.
Change-Id: Ib819413e48a8f9b8d97f596d0fbf771dab211f11
-pkg/server/share.go handles share(d) blobs.
-pkg/blobserver/gethandler no longer deals with share blobs
and has been rewritten like the other handlers (no more auth
in there).
-client and signhandler changed accordingly.
-serverconfig: auth moved up in makeCamliHandler
-share parameter added to the user level and low level config.
-share URL is now http(s)://host[:port]/[prefix/]share/sha1-xxxx.
Addresses http://camlistore.org/issue/107
Change-Id: I0a2c07ac1a1e435b141702e0ff06dc8182721d65