Move images from common to LMS that are only used in LMS

OPEN-328
Remove image that is duplicated in LMS and CMS

OPEN-328
Remove duplicate image files

spinner.gif and spinner-on-grey.gif are the same file.
Explicitly give the LMS a spinner.gif file.

OPEN-328
Move wiki icons to the LMS, where they are used

OPEN-328
Rename pl-faculty.png to placeholder-faculty.png

OPEN-328