Handle COPY verb in container quota middleware

The patch fix the ability to bypass the account
quota using the COPY verb. The quotas for destination
container are now checked before the copy.

Change-Id: I9f409ea6c0893f36972aa1fabe31fb143e151ab5
Fixes: bug #1259565
Added docs about the swift_source log field

Change-Id: I934230a006c856de844d8580f3b57f38a9845844
Small efficiency improvement for SLO range GET

If a client sends a GET request with a Range header for a SLO
manifest, SLO would notice this and perform a second GET request, sans
Range header, to retrieve the manifest body. Most of the time, this is
the sane thing to do: a subset of a SLO manifest is pretty much
useless. However, if the client has requested the first N bytes of the
large object, and the SLO manifest has N or fewer bytes, then the
response will actually have the whole manifest in it, so SLO doesn't
need to make a second request. (It's not wrong, just inefficient.)

Fortunately, ranged GET responses come with a Content-Range header
that tells us first byte, last byte, and total content length. Now SLO
detects whether or not a ranged GET response contains the full
manifest, and if so, just uses the existing response instead of making
another.

Change-Id: I63b991e08a1165eb3e88bd0620a1e64ef056fec6
Allow log disable in account/container server

Logging can be disabled in the object server, but not in the
account and container server though both sample configs already
include that setting. This patch allows to disable logging for
account and container server as well.

Functionality is ensured by some additional tests.

Closes-Bug: 1280954
Change-Id: Ia4e87911863089c3bea093d9f181ff29e9e963eb
Merge "Small efficiency improvement for SLO range GET"
Merge "Handle COPY verb in container quota middleware"
Merge "Added docs about the swift_source log field"
Merge "Allow log disable in account/container server"