Fedora uses em1 for undercloud/overcloud

Updates the devtest_undercloud.sh and devtest_overcloud.sh
scripts to account for the fact that Fedora uses em1
as the default NeutronPublicInterface name.

Change-Id: I4b4bb7b6a25b058eebe889fd8ce1a403aaf193fd
Merge "Fedora uses em1 for undercloud/overcloud"