Permit selecting storage service internal as a location type

refs #6819
Do not recreate internal space if one already exists

Previously, if the storage service internal location was changed to a
new location, this startup function would create a new one at the
default path. This now only tries to make a new internal location if
none exists at all.

refs #6819
Add email notification for deletion requests, fixity failures
Add link to download packages from Packages tab

refs #6929