Restrict the length of the Security Group name input

There is an allowed maximum length for security group name field, but in
current code, it doesn't check or restrict that from UI side, i.e. user
will be able to type in more than what is allowed. After form
submission, it will fail but there is no clear message telling user what
caused failure.

After adding the code to restrict the max length of the security group
name field, user will not be able to input more than what is allowed,
thus this error will be prevented from UI.

Change-Id: I0f560e78e67a0259343f1a2c820270506653b254
Closes-Bug: #1279472
Merge "Restrict the length of the Security Group name input"