fs: don't log entire write contents

Change-Id: Ib9e89916e55020ecd498b32230ae8dc189a0116d
pkg/server: actually use the image format

http://camlistore.org/issue/289

Change-Id: Id1f344e567349ed8d540357bfb397252ac131456
schema: fix blob.Builder JSON clone bug; issue 305

Change-Id: I8ef981f96abdac1a7e2c101e1c9c3cde52fb6f5f