ismount should not raise exceptions

The changes from using os.path.ismount to using
swift.common.utils.ismount has caused problems since the new one
raises exceptions in cases where the old one did not. Daemons have
been encountering this and exiting; servers have been 500ing instead
of 507ing in this case, changing handoff behaviors, etc.

Since the new one was specifically written and tested for this new
behavior, I left that original function as ismount_raw and made
ismount do what it did before.

If there really isn't some reason for this new behavior, I'll be glad
to get rid of ismount_raw and just keep ismount. I couldn't see any
reason for the new behavior myself.

Change-Id: I2b5b17f9ed9656cd8804a5ed568170697d0b183d
Add documentation for GateKeeper

The purpose of GateKeeper mostly relates to the development of new swift code,
so I threw together a guide for development_middleware that covers some basics
with a eye towards metadata handling in-particular.

I also fixed up some missing autodoc's, split out middleware autodoc and added
some ref's here and about so I could link to them from the
development_middleware guide.

DocImpact
Change-Id: I20dd942ea8df9e33c3e794cb49669ffa1332c63e
Move test.unit.locale out of gettext's way

When I run unittests on my laptop I get an ImportError from gettext who tries
to "from locale import normalize" and says "ImportError: cannot import name
normalize".  Whit this patch unittests works, not sure why this problem
doesn't show up in my other dev environments.

Also this seems like good form since 'locale' is already a stdlib module.

Change-Id: If0fcd66ce391665b4e4127c610de3246db409a68
Merge "Add documentation for GateKeeper"
Merge "ismount should not raise exceptions"
Add flag to stop swob from always using absolute location.

This is needed for SOS (along with patch
https://github.com/dpgoetz/sos/pull/37)
to work with swift 1.12 . By spec you should always use the absolute
location but this causes a problem with staticweb over a cdn using a
cname. Basically you want to be able to forward the browser to a
relative location instead of whatever full url the proxy server
thinks you are using.

Change-Id: I3fa1d415bf9b566be069458b838f7e65db0c4f39
Merge "Move test.unit.locale out of gettext's way"