GreenDBConnection no longer assumes that arguments are kwargs

Previous this code assumed that almost all arguments would be passed
as kwargs. Now the code also handles ``timeout`` occurring in
``*args``. This is needed because on PyPy's sqlite module, they are
passed in ``*args``.

Change-Id: I7ce25e7b262c6f46680e3f0eb391094de8051946
Add option to return disk usage report with byte suffix.

Disk usage is currently returned as bytes. This patch adds the option
to return the value with a more human-friendly suffix, eg. MB/GB/TB/PB.

Change-Id: I3d55181f7e6085e711bd6e09ea2ce0a12b290cc5
Merge "GreenDBConnection no longer assumes that arguments are kwargs"
Merge "Add option to return disk usage report with byte suffix."