Fix for null mimetypes in os_files alter #3513

Made sure to check if a mimetype was null before array merging it.  When they are empty, use the array we would have merged with.
Merge branch 'SCHOLAR-3.x' into 3513-os_files_null_merge

Conflicts:
	openscholar/modules/os/modules/os_files/os_files.module
Add fields.
Change og_node_access_strict.
Set og_node_access_strict:
Fix update.
Add submit handler.
Prevent error.
sort extensions alphabetically
fields extensions.
more fields.
fix media gallery
Remove obsolete code.
Remove site wide "vsite user" role.
Merge branch 'SCHOLAR-3.x' into 4374
Add vsite::og_is_group_admin().
Better handle OS boxes.
Fix typo.
Merge branch 'os-boxes' into 4374
Revert "Merge branch 'os-boxes' into 4374"

This reverts commit 7239f045f2b4aed159b0bf8d05a929add00e43d9, reversing
changes made to 91ea099868fa066fc6cd2e428fe2531487a44cb7.