changed back some of the standard colors for warnings/alerts/etc.
Merge branch 'css-refactor' of https://github.com/goehle/webwork2 into testing/css-refactor

# By Geoff Goehle
# Via Geoff Goehle
* 'css-refactor' of https://github.com/goehle/webwork2:
  Cleaned up red theme a little and added hover color

Conflicts:
	htdocs/themes/math4-red/math4-coloring.css
Merge pull request #5 from pstaabp/testing/css-refactor

Testing/css refactor