Following commit introduces using composite
paste file to describe application pipelines.
With the help of composite feature it was possible to
define 4 distinct supapplications, each having different
pipeline setup:
* version_app => no keystoneauth, simple data return with error trap
* healthcheck_app => no keystoneauth, simple data return with error trap
* api_v2 => as it was, added error_trap though
* api_v3 => as it was, added error_trap though
Following approach opens up the possibilities of modelling an API
in far more flexible way and removes the need of any hacking inside
the codebase.
Note:
Keeps backward compatibility with older codebase.
Extra:
* removed dirty hack around skipping certain request.path
in keystonemiddleware (now described in paste file)
* removed 404 when issuing ```curl api_host:api_port/```. Request
is redirected down to VersionApp
Depends-On: I0323eacb5cbba8418550e3322189104c35cf4c36
Change-Id: I873e1376665c8cf66c8ee503975324f9b93ddb45