Wrap table cell contents instead of CSS truncation (thoughtbot#482)

* Wrap table cell contents instead of CSS truncation

This allows table cell contents to wrap to a new line instead of
overflowing the cell's max width, and will also force line breaks on
strings of text that are too long without a natural break.

* Remove table wrapping CSS

The word-wrap property doesn't help unless the column width is fixed, so
return this to close to the default.

app/assets/stylesheets/administrate/base/_tables.scss

@@ -20,8 +20,4 @@ td {
   font-kerning: normal;
   font-variant-ligatures: common-ligatures, contextual;
   font-variant-numeric: lining-nums, tabular-nums;
-  overflow: hidden;
-  text-overflow: ellipsis;
-  white-space: nowrap;
-  word-wrap: normal;
 }