PERF: remove oga gem

oga gem is automatically required by the aws gem
the oga gem retains about 1mb of memory, aws now uses nokogiri

This also removes the html normalize from the pretty text specs that was
a fair bit buggy as the polls test shows.

Gemfile.lock

@@ -41,7 +41,6 @@ GEM
     annotate (2.7.2)
       activerecord (>= 3.2, < 6.0)
       rake (>= 10.4, < 13.0)
-    ansi (1.5.0)
     arel (8.0.0)
     ast (2.3.0)
     aws-partitions (1.24.0)
@@ -200,9 +199,6 @@ GEM
       multi_json (~> 1.3)
       multi_xml (~> 0.5)
       rack (>= 1.2, < 3)
-    oga (2.10)
-      ast
-      ruby-ll (~> 2.1)
     oj (3.1.0)
     omniauth (1.6.1)
       hashie (>= 3.4.6, < 3.6.0)
@@ -334,9 +330,6 @@ GEM
       rainbow (>= 2.2.2, < 3.0)
       ruby-progressbar (~> 1.7)
       unicode-display_width (~> 1.0, >= 1.0.1)
-    ruby-ll (2.1.2)
-      ansi
-      ast
     ruby-openid (2.7.0)
     ruby-prof (0.16.2)
     ruby-progressbar (1.9.0)
@@ -459,7 +452,6 @@ DEPENDENCIES
   multi_json
   mustache
   nokogiri
-  oga
   oj
   omniauth
   omniauth-facebook