Remove httplib2, replace with Requests (#3674)

* Core: remove httplib2, replace with Requests

Additionally remove make_exception in favor of from_http_status and from_http_response.

* Datastore: replace httplib2 with Requests

* DNS: replace httplib2 with Requests

* Error Reporting: replace httplib2 with requests

* Language: replace httplib2 with Requests

* Logging: replace httplib2 with requests

* Monitoring: replace httplib2 with Requests

* Pubsub: replace httplib2 with Requests

* Resource Manager: replace httplib2 with Requests

* Runtimeconfig: replace httplib2 with Requests

* Speech: replace httplib2 with Requests

* Storage: replace httplib2 with Requests

* BigQuery: replace httplib2 with Requests

* Translate: replace httplib2 with Requests

* Vision: replace httplib2 with Requests

Author: Jon Wayne Parrott

google/cloud/error_reporting/_logging.py

@@ -37,8 +37,10 @@ class _ErrorReportingLoggingAPI(object):
                         ``_http`` object is passed), falls back to the default
                         inferred from the environment.
 
-    :type _http: :class:`httplib2.Http` or class that defines ``request()``.
-    :param _http: An optional HTTP object to make requests. If not passed, an
+    :type _http: :class:`~requests.Session`
+    :param _http: (Optional) HTTP object to make requests. Can be any object
+                  that defines ``request()`` with the same interface as
+                  :meth:`requests.Session.request`. If not passed, an
                   ``_http`` object is created that is bound to the
                   ``credentials`` for the current object.
                   This parameter should be considered private, and could

google/cloud/error_reporting/client.py

@@ -90,8 +90,10 @@ class Client(ClientWithProject):
                         ``_http`` object is passed), falls back to the default
                         inferred from the environment.
 
-    :type _http: :class:`httplib2.Http` or class that defines ``request()``.
-    :param _http: An optional HTTP object to make requests. If not passed, an
+    :type _http: :class:`~requests.Session`
+    :param _http: (Optional) HTTP object to make requests. Can be any object
+                  that defines ``request()`` with the same interface as
+                  :meth:`requests.Session.request`. If not passed, an
                   ``_http`` object is created that is bound to the
                   ``credentials`` for the current object.
                   This parameter should be considered private, and could