index: fix data race on BlobSource, make it private.

index.New was starting outOfOrderIndexerLoop in a goroutine. And
outOfOrderIndexerLoop had an if index.BlobSource == nil check, on which
it relied to go on. However, since BlobSource was public and unguarded,
the following sequence was possible:

ix, _ := index.New()
ix.BlobSource = bs

which is racy because the BlobSource assignment may or may not happen
before the check within outOfOrderIndexerLoop.

TestOutOfOrderIndexing was relying on the fact that apparently most
of the time the assignment seems to be happening before the check.

This patch:
-makes BlobSource (now blobSource) private, rendering the race impossible
out of the index package.
-moves the initialization of blobSource, as well as the execution of
outOfOrderIndexerLoop at a unique point, in InitBlobSource (new method).
-makes sure all accesses to blobSource are guarded with the index mutex
(now a RWMutex).

Context: while working on tests for http://camlistore.org/issue/454

Change-Id: I9605f26b41abd62b42880be0620b06ce143761bc
Merge "index: fix data race on BlobSource, make it private."
importer/picasa: a couple schema changes

-album: removed Name attribute. It seems like a valid entry from the feed
(picago indeed gets value), but it is not referenced anywhere in
https://developers.google.com/picasa-web/docs/2.0/reference and it seems
to have the same value as Title anyway.

-photo: removed broken (and redundant with camliContent if not broken)
camliPath.

-s/ID/picasaId/

Change-Id: I5389d825eae83b7618f282698a43c94be6ca8df3
Merge "importer/picasa: a couple schema changes"
Don't do local navigation if a modifier key is pressed.

Change-Id: I8e3996628f8c247652c8a51a8bcf602d5bdfef02
Merge "Don't do local navigation if a modifier key is pressed."
picasa importer: remove context Transports

A more complete version of Aaron Boodman's
https://camlistore-review.googlesource.com/#/c/3066/
in removing Transports.

As Aaron pointed out,
(https://groups.google.com/d/msg/camlistore/9OwQKH6z7rY/840oQrRgsGIJ)
it is illegal for oauth.Transport.Transport to ever be another instance
of oauth.Transport.

Change-Id: I4defb346abfcf3f6c17597fc2dc23a6e536eda37