Improved Excerpts. Updated Version to 1.9.3.

Added updates for improving excerpts, including enabling the ability to
add a read more link. Also made several touch ups to layout.less and
updated all the descriptors on the less files. Version update to 1.9.3,
All changed files now say "Since 1.9.3" and the less files now say
"since" the last time they were updated instead of simply the current
version.