Mark a sir-trevor widget as disabled if you cannot add another of that type
Merge pull request #616 from sul-dlss/widget-restrict-disabled

Mark a sir-trevor widget as disabled if you cannot add another of that type
Fix horizontal spacing on featured items widget.
Merge pull request #618 from sul-dlss/featured-item-spacing

Fix horizontal spacing on featured items widget.
Add content-block (sir-trevor block class) to all custom blocks and add top/bottom margin to it.
Merge pull request #620 from sul-dlss/vertical-spacing

Add content-block (sir-trevor block class) to all custom blocks and add top/bottom margin to it.
Make display_sidebar true by default for pages.