Fix CSV errors for rendering (#514)

templates/pages/gist.html

@@ -55,7 +55,7 @@
             </div>
             <div class="overflow-auto">
                 {{ if $file.MimeType.IsText }}
-                {{ if $file.MimeType.IsCSV }}
+                {{ if eq $file.InternalType "CSVFile" }}
                     <table class="csv-table">
                         <thead>
                             <tr>

templates/pages/gist_embed.html

@@ -17,7 +17,7 @@
             </div>
             {{ end }}
             {{ if $file.MimeType.IsText }}
-            {{ if $file.MimeType.IsCSV }}
+            {{ if eq $file.InternalType "CSVFile" }}
             <table class="csv-table">
                 <thead>
                 <tr>