pkg/blob: Introuduce a type that wraps a blob ref with the blob data.

This new type (blob.Blob) will be used to implement a blob streaming
interface for the storage engines.

Change-Id: I05f3a68022368cf9c7b4a98cced3098ba3965799
Fix bug 279: We sometimes show duplicate images after upload

Change-Id: If1b633f8c0b7c358aa0d2679f4c95db545237e65
Merge "Fix bug 279: We sometimes show duplicate images after upload"
C+A: add Brian Gitonga (Individual CLA)

Change-Id: I00b59812ee1bdab52f5ae24f0ff84acb1dbb322d
Merge "pkg/blob: Introuduce a type that wraps a blob ref with the blob data."
Merge branch 'master' of https://camlistore.googlesource.com/camlistore