Add API modifiers to limit returned toots from public/hashtag timelines

to only those from local users; Add link to "extended information" to
getting started in the UI; Add defaults for posting privacy; Change
how publish button looks depending on posting privacy chosen

app/assets/stylesheets/components.scss

@@ -28,15 +28,7 @@
   }
 
   &.button-secondary {
-    background-color: $color1;
-
-    &:hover {
-      background-color: $color1;
-    }
-
-    &:disabled {
-      background-color: $color3;
-    }
+    //
   }
 }