Introduce an advanced option for Full Content or Excerpt

We follow a chain of defaults for displaying content on archive
pages that starts with a manual post excert if available, then to
a split on the More link if available, and now a check for an
option to force either an auto generated excerpt display or the
full content.
Add a space between the manual excerpt and more link
Mini review, code style formatting
Merge pull request #131 from washingtonstateuniversity/excerpt-or-content

[PR] Introduce an advanced option for Full Content or Excerpt