Validate bool value using strutils.bool_from_string method

Validate bool value using strutils.bool_from_string method

bool value is validated with different logic scattered all over the places
1. isinstance of six.string_type or bool
2. is_valid_boolstr method

Made changes to use strutils.bool_from_string method to validate bool
value at all places as this method does all things expected above.
Changes are not made in v1 api as it is going to be deprecated in
Liberty release.

Example error message:
Invalid value for force_host_copy: Unrecognized value 'xyz', acceptable
values are: '0', '1', 'f', 'false', 'n', 'no', 'off', 'on', 't', 'true',
'y', 'yes'

ApiImpact: 400 BadRequest response will be returned in case invalid force
value is provided during volume upload to image, earlier it was ignored.

Closes-Bug: 1460575
Change-Id: Ie64d429f5860a950cda9b363a65c5282f128f10b