oslo-sync of low hanging fruit

Generated with:
 ./update.sh --base novaclient --config-file
../python-novaclient/openstack-common.conf --dest-dir
../python-novaclient/

Skipped modules: apiclient and cliutils due to oslo issue in apiclient
(cliutils depends on apiclient).
https://review.openstack.org/#/c/76718/

Removed non-existent modules from openstack-commit.conf:
  py3kcompat I06b90f789ae21f2ef8b8071b4298bfc0406482a6
  intall_venv_common I84267f3c6726cb2e750f615e107c48b12c6ed353

Synced patches:
__init__.py [first sync]:
   c178e56 Add basic Python 3 tests
  12bcdb7 Remove vim header
  547ab34 Fix Copyright Headers - Rename LLC to Foundation
  96b9a54 Rajaram/Vinkesh|Added nova's serializaiton classes into common
  c85e1f7 Initial skeleton project

gettextutils:
  6d55e26 Add support for translating log levels separately
  afdbc0a Fix E501 in individual openstack projects
  6b2d15f Merge "Add support for locales missing from babel"
  9d529dd Make Message keep string interpolation args

importutils:
  885828a Deleted duplicated method in cliutils.

strutils:
  bec3a5e Implements SI/IEC unit system conversion to bytes

timeutils:
 d815087 Merge "Fix spelling errors in comments"
 71208fe Fix spelling errors in comments

Change-Id: I8f82acb63e61a64eeb6caba9d2d9c81d9cb766d8
Fix in in novaclient, to avoid excessive conns

The current client creates new .Session() on each request,
but since Horizon is a stateless app, each Session creates
new HttpAdapter, which itself has its own connection pool,
and each connection there is used (almost) once and then
is being kept in the pool(with Keep-Alive) for a certain
amount of time(waiting for inactivity timeout). The problem
is that the connection cannot be used anymore from next Django
calls - they create new connection pool with new connections, etc.
This keeps lots of open connections on the server.

Now the client will store an HTTPAdapter for each URL into
a singleton object, and will reuse its connections between
Django calls, but still taking advantage of Sessions during
a single page load(although we do not fully use this).

Note: the default pool behavior is non-blocking, which means
that if the max_pool_size is reached, a new connection will
still be opened, and when released - will be discarded.
It could be useful to add max_pool_size param into settings,
for performance fine-tuning. The default max_pool_size is 10.

Since python-novaclient is also used from non-Django projects,
I'd expect feedback from more people on the impact this change
could have over other projects.

Patch Set 3: Removed explicit connection closing, leaving
connections open in the pool.

Change-Id: Icc9dc2fa2863d0e0e26a86c8180f2e0fbcd1fcff
Closes-Bug: #1247056
oslo sync apiclient and cliutils

Generated with:
 ./update.sh --base novaclient --config-file
../python-novaclient/openstack-common.conf --dest-dir
../python-novaclient/

Synced patches:

apiclient:
  04a1abe Revert "Removed set_loaded() method from Resource class"
  5e76477 Merge "Handle 300 status code in common HTTPClient"
  492fe2c Merge "py3kcompat: remove"
  466ad64 Merge "Fix usage of dict.keys in apiclient.exceptions"
  8630a44 Merge "Removed set_loaded() method from Resource class"
  41fbfea Merge "Add to_dict() method to apiclient Resource"
  6650435 Fix usage of dict.keys in apiclient.exceptions
  35dc1d7 py3kcompat: remove
  9f1e7eb Correct docstring in load_plugin_from_args
  0c4d2c7 Removed set_loaded() method from Resource class
  3b248dd Add to_dict() method to apiclient Resource
  71c22e9 Handle 300 status code in common HTTPClient

cliutils:
  9a7f2f8 Merge "Deleted duplicated method in cliutils."
  8f2effd Use `six.text_type` instead of `str` in cliutils
  885828a Deleted duplicated method in cliutils.
  71a2d90 Add common methods to cliutils

Change-Id: I0c8849d8d5dd71f34aa5dbcd2c0875c164706d70
Merge "oslo-sync of low hanging fruit"
Merge "oslo sync apiclient and cliutils"
Merge "Fix in in novaclient, to avoid excessive conns"