Honour the verbosity setting in the config file

Previously, the 'verbosity' setting in the config file was always ignored.
We now honour it, but still allow it to be overridden on the commandline.
Merge pull request #284 from swiftserve/fix_config_file_verbosity

Verbosity setting in the config file is ignored
set content-type, content-charset, and not content-encoding

Patches originally by adoliver, rebased for current master branch.

Content-Encoding should only be set by the HTTP server, not by us.
use ~/.s3cfg in run-tests too
move empty object name detection where it belongs

Commit 9679f269 added empty object name detection.  But that was done
"too far down" - it needs to be done when the list is first read from
S3, not later every time the list is iterated.
delete unused keys_to_remove logic
s/0o775/0755/ for python 2.4 compatibility
(feature)Introducing batch_mode in bucket deletion to delete contents without getting the full list
s3.object_batch_delete() function added, rb operation uses batch delete to remove keys prior to bucket deletion
useless comment remove
object_batch_delete() gets full remote_list (consistent with _do_deletes())
getting sequential batches for dealing with S3s eventual consistency
Updates for handling of verbosity config option

* Accept either integers or loglevel names in ~/.s3cfg
* When dumping config, convert integers to loglevel names if possible

This fixes #285.
Merge pull request #286 from swiftserve/fix_verbosity_config

Updates for handling of verbosity config option
batch_delete fixed, subcmd_batch_del() added and replaced _do_deletes()
conflict merge
resolve conflicts
merge with remote master