Swift Multi-tenant store: Pass context on upload

Image upload returns an E500 as the context is not being
passed to the swift client.

Change-Id: I2065b7dd281bfbb513f13270a0c062fc7132f763
Partial-bug: 1385213
Fix context storage bug

Fix a bug with storing the request context in thread local where the
storage was not properly cleared between requests.

(This was causing the same request to always be logged.)

Closes-Bug: 1384911
Change-Id: Ie30b93900451b0f9f6fd8158457b0b66903af470
Merge "Swift Multi-tenant store: Pass context on upload"
Initiate deletion of image files if the import was interrupted

If the image is deleted by appropriate API call while its content
is still being uploaded in import task in v2, an exception is raised
and it is not handled in the API code. This leads to the fact that
the uploaded image file stays in a storage and clogs it.

There existed code that safely removes image files if the exception
occurs.

Change-Id: I4f7d1aa103f4ce7abf4026e7097b9e76c24135fa
Closes-Bug: 1371118
Merge "Fix context storage bug"
Merge "Initiate deletion of image files if the import was interrupted"