Make base search url a member of the request class

Since the request class is loaded prior to values being read from the
user's dotenv, the WHOOGLE_RESULT_PER_PAGE var wasn't being used for
searches.

This moves the definition of the base search url to be intialized in the
request class to address this issue.

Fixes #497

app/request.py

@@ -9,8 +9,6 @@ import os
 from stem import Signal, SocketError
 from stem.control import Controller
 
-SEARCH_URL = 'https://www.google.com/search?gbv=1&num=' + str(
-    os.getenv('WHOOGLE_RESULTS_PER_PAGE', 10)) + '&q='
 MAPS_URL = 'https://maps.google.com/maps'
 AUTOCOMPLETE_URL = ('https://suggestqueries.google.com/'
                     'complete/search?client=toolbar&')
@@ -151,6 +149,8 @@ class Request:
     """
 
     def __init__(self, normal_ua, root_path, config: Config):
+        self.search_url = 'https://www.google.com/search?gbv=1&num=' + str(
+            os.getenv('WHOOGLE_RESULTS_PER_PAGE', 10)) + '&q='
         # Send heartbeat to Tor, used in determining if the user can or cannot
         # enable Tor for future requests
         send_tor_signal(Signal.HEARTBEAT)
@@ -224,7 +224,7 @@ class Request:
         return [_.attrib['data'] for _ in
                 root.findall('.//suggestion/[@data]')]
 
-    def send(self, base_url=SEARCH_URL, query='', attempt=0,
+    def send(self, base_url='', query='', attempt=0,
              force_mobile=False) -> Response:
         """Sends an outbound request to a URL. Optionally sends the request
         using Tor, if enabled by the user.
@@ -285,7 +285,7 @@ class Request:
                     disable=True)
 
         response = requests.get(
-            base_url + query,
+            (base_url or self.search_url) + query,
             proxies=self.proxies,
             headers=headers,
             cookies=cookies)
@@ -295,6 +295,6 @@ class Request:
             attempt += 1
             if attempt > 10:
                 raise TorError("Tor query failed -- max attempts exceeded 10")
-            return self.send(base_url, query, attempt)
+            return self.send((base_url or self.search_url), query, attempt)
 
         return response