Clarified country filter, updated invidious result URL (closes #123)

Improves clarity of the meaning behind the "Country" filter -- Google
seemingly uses this value to only return results that are hosted in a
particular country, as evidenced in the search differences highlighted
in #123. It now mentions that the results are filtered by website
hosting location.

Also, now that invidio.us is shut down, the fallback URL (invidiou.site)
is now used instead.

app/models/config.py

@@ -52,7 +52,7 @@ class Config:
     ]
 
     COUNTRIES = [
-        {'name': 'Default (use server location)', 'value': ''},
+        {'name': 'Default (none)', 'value': ''},
         {'name': 'Afghanistan', 'value': 'countryAF'},
         {'name': 'Albania', 'value': 'countryAL'},
         {'name': 'Algeria', 'value': 'countryDZ'},

app/templates/index.html

@@ -45,7 +45,7 @@
                 <div class="config-fields">
                     <form id="config-form" action="/config" method="post">
                         <div class="config-div">
-                            <label for="config-ctry">Country: </label>
+                            <label for="config-ctry">Filter Results by Country: </label>
                             <select name="ctry" id="config-ctry">
                                 {% for ctry in countries %}
                                     <option value="{{ ctry.value }}"
@@ -56,6 +56,7 @@
                                     </option>
                                 {% endfor %}
                             </select>
+                            <div><span class="info-text"> — Note: If enabled, a website will only appear in the results if it is *hosted* in the selected country.</span></div>
                         </div>
                         <div class="config-div">
                             <label for="config-lang-interface">Interface Language: </label>

app/utils/filter_utils.py

@@ -18,7 +18,7 @@ BLACKLIST = [
 
 SITE_ALTS = {
     'twitter.com': 'nitter.net',
-    'youtube.com': 'invidio.us',
+    'youtube.com': 'invidiou.site',
     'instagram.com': 'bibliogram.art/u'
 }