Convert scripts to entry points

The executable programs used by Glance have historically been scripts
in the ./bin directory.  This patch converts all of the scripts to
entry_points.  This change makes these programs python modules.  Thus
they can be imported and methods in them can be called just like any
other module.  This will allow the tests to call into these programs
directly instead of having to fork out a process.

The conf.py file in the doc tree was causing a name collision with
the python module cmd.  The glance/glance directory was being added
to sys.path which made glance.cmd import with the name cmd.  This
patch also fixes that problem.

blueprint: refactoring-better-faster-stronger-functional-tests
Change-Id: I67ae14b7403af31a5944befcd2ec27a690e81f15
Merge "Convert scripts to entry points"