tests.cmdlib: Test index operations
tests.cmdlib: Test index operations

Test if the GetIndexFromIdentifier and InsertItemToIndex functions work
properly.

Signed-off-by: Alex Pyrgiotis <6383a799dda2258eec8fa26a3ce2ec8a7d552341@grnet.gr>
Signed-off-by: Aaron Karper <99cc1031546340b2b8ced5fe338b5890677a56ca@google.com>
Reviewed-by: Aaron Karper <99cc1031546340b2b8ced5fe338b5890677a56ca@google.com>

apyrgio/ganeti,andir/ganeti,onponomarev/ganeti,mbakke/ganeti,mbakke/ganeti,andir/ganeti,leshchevds/ganeti,grnet/snf-ganeti,andir/ganeti,mbakke/ganeti,ganeti/ganeti,ganeti/ganeti,ganeti/ganeti,dimara/ganeti,leshchevds/ganeti,yiannist/ganeti,onponomarev/ganeti,bitemyapp/ganeti,grnet/snf-ganeti,yiannist/ganeti,dimara/ganeti,leshchevds/ganeti,apyrgio/ganeti,bitemyapp/ganeti,yiannist/ganeti