use a session instead of requests directly

     * enable persistent sessions to be used instead of an always-new
       session for each request

analysisstore/client/asutils.py

@@ -5,8 +5,11 @@
 import six
 
 
+session = requests.Session()
+
+
 def get_document(url, doc_type, as_json, contents):
-    r = requests.get(url, params=ujson.dumps(contents))
+    r = session.get(url, params=ujson.dumps(contents))
     r.raise_for_status()
     content = ujson.loads(r.text)
     if as_json:
@@ -18,7 +21,7 @@ def get_document(url, doc_type, as_json, contents):
 
 def post_document(url, contents):
     try:
-        r = requests.post(url, data=ujson.dumps(contents))
+        r = session.post(url, data=ujson.dumps(contents))
     except ConnectionError:
         raise ConnectionError('No AnalysisStore server found')
     r.raise_for_status()  # this is for catching server side issue.