Enable osprofiler interface in glanceclient shell

To help end user uses profiling by glanceclient CLI directly, the
change added '--profile <HMAC_KEY>' argument to the shell.

This change also fixed a function regression, it was used to pass
necessary trace info to glance server via http header:
https://github.com/openstack/python-glanceclient/commit/dbb242b776908ca50ed8557ebfe7cfcd879366c8#diff-740dd7d9149f46fe4c01ef0ab7eb3bfbL196

In addition:
1. If client app want to enable profiling feature for glanceclient
object, please see: http://paste.openstack.org/show/85722/
2. Afer adding more trace point into Client object, as fundamental
requirement of osprofiler, what we need to notice caller is providing
correct messaging notifier in the context code.

The relevant change for glance server is ready at:
I45a19f5eb5304c2b78a9e12cbc0744941a807304

DocImpact

Change-Id: If42b69b2695a5f88536ecbc2c1b3592d9dbd880a
Signed-off-by: Zhi Yan Liu <lzy.dev@gmail.com>
Ensure server's SSL cert is validated

A bug was introduced which meant that the server SSL certificate was
not being verified. Here we make sure that it is checked (unless
the --insecure flag is used).

Helps guard against man-in-the-middle attack.

Change-Id: I08f30bf3906b6580c871729311343fa8eefda91b
Closes-bug: #1357430
Merge "Enable osprofiler interface in glanceclient shell"