Update except statements to use `as` everywhere.
Require python >= 2.6, use the json module.

* Set the minimum version of python to be 2.6, since we don't need to support
  anything older anymore.

* As the first of a series of related cleanups, drop our custom json
  module (since json is in the stdlib since 2.6).
Merge pull request #36 from craigcitro/imports

Require python >= 2.6, use the json module.
Assorted import/lint cleanup.

This is mostly a cleanup around import statements and a few related pylint
issues.
Merge pull request #37 from craigcitro/imports2

More import/lint cleanup.
Drop uritemplate.

The `uritemplate` module was only used in one place, for what amounted mostly
to a string replace, so we can simply drop it. Unfortunately the `META`
variable in that file is part of the public interface, so we need to keep it
around as-is.
Merge pull request #38 from craigcitro/imports3

Drop uritemplate.
Merge branch 'master' into six-cleanup

Conflicts:
	oauth2client/client.py
	oauth2client/clientsecrets.py
	oauth2client/crypt.py
	oauth2client/file.py
	oauth2client/gce.py
	oauth2client/multistore_file.py
	oauth2client/service_account.py
	oauth2client/tools.py
	oauth2client/util.py
	tests/test_jwt.py
	tests/test_oauth2client.py
	tests/test_service_account.py
	uritemplate/__init__.py
Fix errors.
Cleanup client.py
cleanup client.py
Cleanup