Base.get_engine honor allow_global_engine=False

This change makes it so that get_engine() in
keystone.common.sql.core.Base does not return the global engine
when allow_global_engine is False.

The behavior before could be described like:
If get_engine() has never been called with allow_global_engine=True,
then if you pass allow_global_engine=False returns a new engine.
Otherwise, you always get the global engine (even if
allow_global_engine=False)

The new behavior is:
If get_engine() is called with allow_global_engine=True then
it returns the global engine, otherwise it returns a new engine.

Change-Id: I756b54d9f3984733f56d09c11b2702c3451102f2
python WebOb dependency made unpinned.

keystone declares python-webob dependency as ==,
which is not a good way of defining dependency.
So to support latest dependencies, WebOb is unpinned in
requirements.txt

Fixes: bug #1180033
Change-Id: I73042cf88baf378c8564abb2394963866082977e
Fix link typo in Sphinx doc

Change-Id: I00667ca171d1be5acdacb472561cbf74baf6a852
Initialize logging from HTTPD.

Fixes bug 1190324

Change-Id: I6031c26c4917bd526c5918d815bff3bd060301c8
Consolidate admin_or_owner rule

admin_or_owner rule has already defined at the beginning for the file.
Make use of it.

Change-Id: I18f1d96aaba095d05e770b3d564a255659de23ce
wsgi.Middleware factory should use **kwargs

Fixes bug 1190978

Change-Id: Ifb0673b7aab5292c13bf5c86c5cc2de8096f7e3e
Merge "Fix link typo in Sphinx doc"
Merge "Base.get_engine honor allow_global_engine=False"
Merge "python WebOb dependency made unpinned."
Merge "Initialize logging from HTTPD."
Merge "wsgi.Middleware factory should use **kwargs"
Merge "Consolidate admin_or_owner rule"