owncloud: Add packages for external storage
owncloud: Add packages for external storage

The two packages are required when External Storage plugin in ownCloud
is enabled.  Since this has been a frequently asked question, add it to
the dependencies list.

harry-7/Plinth,freedomboxtwh/Plinth,kkampardi/Plinth,vignanl/Plinth,freedomboxtwh/Plinth,vignanl/Plinth,kkampardi/Plinth,vignanl/Plinth,kkampardi/Plinth,kkampardi/Plinth,vignanl/Plinth,freedomboxtwh/Plinth,harry-7/Plinth,harry-7/Plinth,kkampardi/Plinth,vignanl/Plinth,harry-7/Plinth,harry-7/Plinth,freedomboxtwh/Plinth,freedomboxtwh/Plinth