Check for new files as well as changed files
Check for new files as well as changed files

Currently, the run-compare-xml.sh script will only report changed or
removed files, it does not report new files being created. This change
replaces diff in a for loop with a recursive diff that treats missing
files as empty files. The result is that the output is presented as a
single unified diff that includes new files as well as changed and
removed files.

Change-Id: I0bb5a1ee93e689666ca5080ec5ccbe036c73d682

noorul/os-project-config,anbangr/osci-project-config,coolsvap/project-config,coolsvap/project-config,citrix-openstack/project-config,osrg/project-config,osrg/project-config,Tesora/tesora-project-config,dongwenjuan/project-config,anbangr/osci-project-config,open-switch/infra_project-config,citrix-openstack/project-config,noorul/os-project-config,open-switch/infra_project-config,Tesora/tesora-project-config,dongwenjuan/project-config,openstack-infra/project-config,openstack-infra/project-config