[enh] own useragent handling init

searx/engines/__init__.py

 from operator import itemgetter
 from urlparse import urlparse
 from searx import settings
+from searx.utils import get_useragent
 import ConfigParser
 import sys
 from datetime import datetime
     results = {}
     suggestions = set()
     number_of_searches += 1
-    user_agent = request.headers.get('User-Agent', '')
+    #user_agent = request.headers.get('User-Agent', '')
+    user_agent = get_useragent()
 
     for selected_engine in selected_engines:
         if selected_engine['name'] not in engines:

searx/utils.py

 import cStringIO
 import re
 
+def get_useragent():
+    # TODO
+    return "Mozilla/5.0 (X11; Linux x86_64; rv:26.0) Gecko/20100101 Firefox/26.0"
+
 def highlight_content(content, query):
 
     if not content: