Add/delete NFS pool

Description

Add nfs pool support in kimchi
choose pool type (dir or nfs)
inputs: pool name, nfs server ip, nfs exported path
Pool will be created. activiate and use it

TODO
Wait widget while any kimchi operation in progress
list NFS exported paths
list nfs mount source path

Signed-off-by: Pradeep K Surisetty<psuriset@linux.vnet.ibm.com>
Signed-off-by: zhoumeina <zhmeina@cn.ibm.com>
po files: NFS pool

Add all text related to NFS pool creation to po files

Signed-off-by: Pradeep K Surisetty<psuriset@linux.vnet.ibm.com>
Signed-off-by: zhoumeina <zhmeina@cn.ibm.com>