Small improve of str2dict function

Change-Id: Ifa8974f2cbdac4fdc0cbd47d7ad9910a5bd31cb7
Updated from global requirements

Change-Id: I0628d1071955a7f82efd1e1e054fa38ae1dff006
Leverage openstack.common.jsonutils

This patch removes our own home brewed json helper functions and leverages
the ones from openstack.common.jsonutils instead.

Change-Id: Idc5ee0fec56b0a0f337433a830647d4f421a8283
Closes-bug: 1365263
Merge "Leverage openstack.common.jsonutils"
Merge "Small improve of str2dict function"
Use adapter from keystoneclient

The adapter in keystoneclient is there to abstract the common client
parameters that may be used when sending a request. We should use that
rather than keeping our own methods.

Change-Id: I727ac76babb6f6aef1a0f619c011ad67a6e2fccf