Mark password config options with secret

Config object supports masking values when writing out if the secret
flag is set on the option definition.  This change flags all
python-keystoneclient options containing a password.

Change-Id: I1ffc9727ab66c7acc6d4cf8e5870bb32f5e68b67
Update requests requirements

Bump the version requirements for requests so it does
not conflict with the version of requests required
for glance (unpinned).

Change-Id: I06479b8ceb04df749a6d7f7dc584892a688cd449
Signed-off-by: Chuck Short <chuck.short@canonical.com>