Remove non SP related code

This commit only removes code that is not required when swiftonfile
will be used as Storage Policy in Swift.

This commit does NOT:
* include code changes to support SP
* fix functional tests
* update documentation related to SP

This commit removes the following:
* Gen builders script and its man page.
* Authentication guide, user guide and other docs.
* Swiftkerbauth code, unit tests, func tests and doc.
* gswauth code, unit tests, func tests and doc.
* Object expirer code modifications, unit tests and doc.
* Conf files of account, container, proxy.
* Account, container and proxy server code - server.py of each.
* Account, container and proxy unit and functional tests.
* DiskDir class and corresponding unit tests.
* Our overridden ring.py (enforces account = volume = device) and tests.
* Functional tests for authentication filters.
* modules/swift and test/deploy directories.
* Proxy base controllers unit tests.

NOTE: We may have to reintroduce some of the above functional and unit
tests after SP related code changes - during fixing functional tests.

This commit modifies:
* setup.py to reflect the above code removals.
* constraints.py to remove references to ring.py
* object server.py to remove object-expirer changes
* tox.ini to remove ksfunctest and swfunctest

Signed-off-by: Prashanth Pai <ppai@redhat.com>