Remove both references to get_current_site_name()

This was deprecated in WordPress 3.9 and there should be no reason
for either use. If it's really needed we can find a more appropriate
way to provide the information at a later time.

Closes #49
Merge pull request #56 from washingtonstateuniversity/current-site-name

[PR] Remove both references to get_current_site_name()