junit: refactor v4 test to reduce code duplication

Acked-by: Karsten Schwank
Target: master, 2.7
Require-book: no
Require-notes: no
nfsv3: reply correct auth flavor of mount

The mount protocol should include into reply the list
of security flavors allowed by for the requested export

Acked-by: Karsten Schwank
Target: master
Require-book: no
Require-notes: no