add block elements back into oerpub index file
fix css for note placeholders
fix editing placeholder text
fix editing things with placeholders
fix note plugin mapping errors
fix mapping error with exercises
enable image previews
fix bug when canceling image modal
stop inserting image sources as alt
Revert "add block elements back into oerpub index file"

This reverts commit 78a72257322ed9ca91cd01218892c8bef764a5e6.

Conflicts:

	oerpub/index.html
Merge branch 'block-image' into block-bugfixes
Merge branch 'block-bugfixes' into testing