Remove service argument from tempest plugin client manager

It was removed as part of commit
e4be907e34e043888bb10b29655018dd2d4eb06e to tempest.

Also, fix python3 compatibility for API boolean type

This was throwing errors in the latest WSME on python 3.5, make it the
right string type instead. It must be squashed into this change because
each fixes a different CI job, and they can't land without each other.

Closes-Bug: #1654202
Change-Id: I5cefad7d9d8f6db51fd891ecce9879979c83baee

ironic/api/controllers/v1/types.py

@@ -117,7 +117,7 @@ class BooleanType(wtypes.UserType):
             return strutils.bool_from_string(value, strict=True)
         except ValueError as e:
             # raise Invalid to return 400 (BadRequest) in the API
-            raise exception.Invalid(e)
+            raise exception.Invalid(six.text_type(e))
 
     @staticmethod
     def frombasetype(value):

ironic_tempest_plugin/clients.py

@@ -27,15 +27,13 @@ ADMIN_CREDS = common_creds.get_configured_admin_credentials()
 
 class Manager(clients.Manager):
     def __init__(self,
-                 credentials=ADMIN_CREDS,
-                 service=None):
+                 credentials=ADMIN_CREDS):
         """Initialization of Manager class.
 
         Setup service client and make it available for test cases.
         :param credentials: type Credentials or TestResources
-        :param service: service name
         """
-        super(Manager, self).__init__(credentials, service)
+        super(Manager, self).__init__(credentials)
         default_params_with_timeout_values = {
             'build_interval': CONF.compute.build_interval,
             'build_timeout': CONF.compute.build_timeout