BUG 1383 Cannot compose VNFD from UI: 'mgmt_cp missing' when adding VDU

 * Before adding CP need to VDU
 * While adding CP add mgmt-cp

Change-Id: I4219faea328ab46285f8e049d5dc1a7565cdea42
Signed-off-by: Barath Kumar R <barath.r@tataelxsi.co.in>