webadmin: Added frontend bond name validation

Now that the user may add new bond names, it is necessary to check that
the given name is of the correct format; added a specific validation
class, as well as the code to actually perform the check on the popup
window.

Change-Id: I8f5ea2b582f3117817ef72f7d3350977a124681f
Signed-off-by: Lior Vernia <lvernia@redhat.com>