Add searx_extra package

Split the utils directory into:
* searx_extra contains update scripts, standalone_searx.py
* utils contains the files to build and setup searx.

searx_extra/update/update_firefox_version.py

@@ -0,0 +1,68 @@
+#!/usr/bin/env python
+
+import json
+import requests
+import re
+from os.path import dirname, join
+from urllib.parse import urlparse, urljoin
+from distutils.version import LooseVersion, StrictVersion
+from lxml import html
+from searx import searx_dir
+
+URL = 'https://ftp.mozilla.org/pub/firefox/releases/'
+RELEASE_PATH = '/pub/firefox/releases/'
+
+NORMAL_REGEX = re.compile('^[0-9]+\.[0-9](\.[0-9])?$')
+# BETA_REGEX = re.compile('.*[0-9]b([0-9\-a-z]+)$')
+# ESR_REGEX = re.compile('^[0-9]+\.[0-9](\.[0-9])?esr$')
+
+# 
+useragents = {
+    "versions": (),
+    "os": ('Windows NT 10.0; WOW64',
+           'X11; Linux x86_64'),
+    "ua": "Mozilla/5.0 ({os}; rv:{version}) Gecko/20100101 Firefox/{version}"
+}
+
+
+def fetch_firefox_versions():
+    resp = requests.get(URL, timeout=2.0)
+    if resp.status_code != 200:
+        raise Exception("Error fetching firefox versions, HTTP code " + resp.status_code)
+    else:
+        dom = html.fromstring(resp.text)
+        versions = []
+
+        for link in dom.xpath('//a/@href'):
+            url = urlparse(urljoin(URL, link))
+            path = url.path
+            if path.startswith(RELEASE_PATH):
+                version = path[len(RELEASE_PATH):-1]
+                if NORMAL_REGEX.match(version):
+                    versions.append(LooseVersion(version))
+
+        list.sort(versions, reverse=True)
+        return versions
+
+
+def fetch_firefox_last_versions():
+    versions = fetch_firefox_versions()
+
+    result = []
+    major_last = versions[0].version[0]
+    major_list = (major_last, major_last - 1)
+    for version in versions:
+        major_current = version.version[0]
+        if major_current in major_list:
+            result.append(version.vstring)
+
+    return result
+
+
+def get_useragents_filename():
+    return join(join(searx_dir, "data"), "useragents.json")
+
+
+useragents["versions"] = fetch_firefox_last_versions()
+with open(get_useragents_filename(), "w") as f:
+    json.dump(useragents, f, indent=4, ensure_ascii=False)