Ignore top-level hidden dirs/files by default
Ignore top-level hidden dirs/files by default

Rather than waiting for each contributor to attempt to submit
a change to .gitignore trying to add the $editor_of_the_week
hidden directory just to be rejected, let's just ignore hidden
files/dirs by default in the top-level neutron directory.

Change-Id: I145bec958a3db7423a4e820a310b138ed189d2cc

moshele/old-networking-mlnx