Major main*.py files refactoring.

Major files refactoring - auth_service.

- Migrate auth_server/backend/, common/ and frontend/ into the main application
  directory and rename source files for consistency.
- Enforce debug parameter on all create_application().
- Remove appstats, the new Cloud Console Trace features can give meaningful data
  without require intervention from within the app.

R=vadimsh@chromium.org
BUG=

Committed: https://code.google.com/p/swarming/source/detail?repo=default&r=c043b409936afc92b998802b49ed89577e29c0c0

[M-A, 2015-03-26 14:00:49]

I think it makes the project easier to understand and it makes the layout the
same as other projects.

The remaining difference is 'common' in auth_service vs 'server' in swarming and
dumping in the app directory for isolate. But I don't have an opinion yet on
which layout to prefer. I'd like to settle on one but since I don't have a
preference, I don't know what to choose.

[vadimsh, 2015-03-26 21:37:53]

auth_service/common can be moved at the root (auth_service/), there's much
there.

https://codereview.appspot.com/220250043/diff/40001/appengine/auth_service/ma...
File appengine/auth_service/main_backend.py (left):

https://codereview.appspot.com/220250043/diff/40001/appengine/auth_service/ma...
appengine/auth_service/main_backend.py:16: sys.path.insert(0,
os.path.join(APP_DIR, 'components', 'third_party'))
where protobuf is added to sys.path?

[M-A, 2015-03-27 14:15:46]

Update sys.path, migrate common/ too

[M-A, 2015-03-27 14:17:06]

On 2015/03/26 21:37:53, vadimsh wrote:
> auth_service/common can be moved at the root (auth_service/), there's much
> there.

Done.

https://codereview.appspot.com/220250043/diff/40001/appengine/auth_service/ma...
File appengine/auth_service/main_backend.py (left):

https://codereview.appspot.com/220250043/diff/40001/appengine/auth_service/ma...
appengine/auth_service/main_backend.py:16: sys.path.insert(0,
os.path.join(APP_DIR, 'components', 'third_party'))
On 2015/03/26 21:37:53, vadimsh wrote:
> where protobuf is added to sys.path?

Ah, it's not. Added back. This was simply using the one included in GAE.

[vadimsh, 2015-03-27 20:02:59]

lgtm

[M-A, 2015-03-29 13:13:45]

Committed patchset #2 (id:60001) manually as
c043b409936afc92b998802b49ed89577e29c0c0 (presubmit successful).