Don't reuse request and transport instances

Re-using these instances was causing request failures when talking to
`uwsgi`. I still don't know the exact cause - probably something related
to the headers or even cached in the `http.Client` instance - but this
does fix the current issue and it also makes sense to have a new request
object for every request.

Change-Id: I30f78e048eea7105e4cced4530b165ad7a25d914

zaqarclient/queues/v1/flavor.py

@@ -49,6 +49,7 @@ class Flavor(object):
             data = {'pool': self.pool,
                     'capabilities': self.capabilities}
 
+            req, trans = self.client._request_and_transport()
             core.flavor_create(trans, req, self.name, data)
 
     def update(self, flavor_data):

zaqarclient/queues/v1/pool.py

@@ -58,6 +58,7 @@ class Pool(object):
             if self.client.api_version >= 1.1:
                 data['group'] = self.group
 
+            req, trans = self.client._request_and_transport()
             core.pool_create(trans, req, self.name, data)
 
     def update(self, pool_data):