css: clean up <ul> css.

* Remove `list-style-type: none` rules (this is the default).
* Add `list-bulleted` and `list-inline` utility classes.
* Wrap terms of service and user deletion pages in dtext `.prose` class
  so we don't have to redefine basic list styles on these pages.

app/javascript/src/styles/common/blacklists.scss

@@ -17,9 +17,6 @@
   }
 
   &.sidebar-blacklist ul li {
-    list-style-type: disc;
-    list-style-position: inside;
-
     a {
       max-width: 75%;
     }

app/javascript/src/styles/common/main_layout.scss

@@ -13,10 +13,6 @@ div#page {
       font-size: $h3_size;
     }
 
-    ul {
-      list-style-type: none;
-    }
-
     #options-box i.fa-bookmark {
       margin-right: 0.25em;
     }

app/javascript/src/styles/common/news.scss

@@ -12,7 +12,6 @@ div#news-updates {
   }
 
   li {
-    list-style-type: none;
     float: left;
     margin: 0 2em 0 0;
     padding: 0;