[Part 10] Remove all usage of six library

We don't need this in a Python 3-only world.

Remove six in follows:
1. lower-constraints.txt
2. requirements.txt
3. zaqar/bench/observer.py
4. zaqar/common/api/api.py
5. zaqar/common/api/request.py
6. zaqar/common/api/response.py
7. zaqar/common/pipeline.py
8. zaqar/common/storage/select.py

Change-Id: I8669061e00fd929c24e62ce9fd4ba31aab63e0d4

zaqar/bench/observer.py

@@ -21,7 +21,7 @@ from gevent import monkey as curious_george
 curious_george.patch_all(thread=False, select=False)
 import gevent
 import marktime
-from six.moves import urllib
+import urllib
 from zaqarclient.transport import errors
 
 from zaqar.bench import config

zaqar/common/api/api.py

@@ -33,7 +33,7 @@ class Api(object):
 
         :param action: Action for which params need
             to be validated.
-        :type action: `six.text_type`
+        :type action: `str`
 
         :returns: Action's schema
         :rtype: dict
@@ -57,7 +57,7 @@ class Api(object):
 
         :param action: Action's for which body need
             to be validated.
-        :type action: `six.text_type`
+        :type action: `str`
         :param body: Params to validate
         :type body: dict
 

zaqar/common/api/request.py

@@ -28,7 +28,7 @@ class Request(object):
     :param headers: Request headers. Default: None
     :type headers: dict
     :param api: Api entry point. i.e: 'queues.v1'
-    :type api: `six.text_type`.
+    :type api: `str`.
     :param env: Request environment. Default: None
     :type env: dict
     """

zaqar/common/api/response.py

@@ -24,7 +24,7 @@ class Response(object):
     :param request: The request sent to the server.
     :type request: `zaqar.transport.request.Request`
     :param body: Response's body
-    :type body: `six.string_types`
+    :type body: `str`
     :param headers: Optional headers returned in the response.
     :type headers: dict
     """

zaqar/common/pipeline.py

@@ -32,7 +32,6 @@ them do, an AttributeError exception will be raised.
 import contextlib
 
 from oslo_log import log as logging
-import six
 
 from zaqar.common import decorators
 from zaqar.i18n import _
@@ -58,7 +57,7 @@ class Pipeline(object):
         for `method`.
 
         :params method: The method name to call on each stage
-        :type method: `six.text_type`
+        :type method: `str`
 
         :returns: A callable to consume the pipeline.
         """
@@ -88,7 +87,7 @@ class Pipeline(object):
                 try:
                     target = getattr(stage, method)
                 except AttributeError:
-                    sstage = six.text_type(stage)
+                    sstage = str(stage)
                     msgtmpl = _(u"Stage %(stage)s does not "
                                 "implement %(method)s")
                     LOG.debug(msgtmpl, {'stage': sstage, 'method': method})

zaqar/common/storage/select.py

@@ -25,7 +25,7 @@ def weighted(objs, key='weight', generator=random.randint):
     :param objs: a list of objects containing at least the field `key`
     :type objs: [dict]
     :param key: the field in each obj that corresponds to weight
-    :type key: six.text_type
+    :type key: str
     :param generator: a number generator taking two ints
     :type generator: function(int, int) -> int
     :return: an object