Replace is_valid_boolstr with strutils.bool_from_string method

[Rajesh Tailor]

Replace is_valid_boolstr with strutils.bool_from_string method
to remove code duplication. Also remove is_valid_boolstr method from cinder/utils module.

At some places in code where strutils.bool_from_string is already used but
unnecessary checking of basestring or bool type is also done.

Need to refactor that piece of code and remove unnecessary checking,
as strutils.bool_from_string first convert value to string and returns
accordingly boolean after taking default params into consideration as well.

for eg.:
Example: admin_actions.py->method _migrate_volume

if isinstance(force_host_copy, basestring):
            try:
                force_host_copy = strutils.bool_from_string(force_host_copy,
                                                            strict=True)
            except ValueError:
                raise exc.HTTPBadRequest(
                    explanation=_("Bad value for 'force_host_copy'"))
        elif not isinstance(force_host_copy, bool):
            raise exc.HTTPBadRequest(
                explanation=_("'force_host_copy' not string or bool"))

should be

try:
     force_host_copy = strutils.bool_from_string(force_host_copy, strict=True)
except ValueError:
    msg = _("Invalid value '%s' for force_host_copy.") % force_host_copy
    raise exc.HTTPBadRequest(explanation=msg)

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/187470

[Rajesh Tailor (rajesh-tailor)]

Hi,

In proposed patch, is_valid_boolstr method of cinder/utils module is not removed because it is being used by v1 api.