Anticipate future fix for missing .gitignore in archetypes' projects

Anticipate future fix for missing .gitignore in archetypes' projects

see https://issues.apache.org/jira/browse/MRESOURCES-190 (or
http://stackoverflow.com/questions/7981060/maven-archetype-plugin-doesnt-let-resources-in-archetype-resources-through/37322323#37322323)

BTW: The current solution in
opendaylight-startup/src/main/resources/META-INF/maven/archetype-metadata.xml
doesn't seem to work (for me; I don't get a .gitignore ..). At least
with this it will work when we'll upgrade from current
maven-resources-plugin 2.7 to 3.0 (not yet released) some time in the
future.

PS: The removed /config/.gitignore is an unrelated minor clean.

Change-Id: I3d7d8708eb128d975879094f3775439e11721668
Signed-off-by: Michael Vorburger <vorburger@redhat.com>