Copy initial configuration file in Karaf 4

Fix copying of initial configuration file in Karaf 4. Problem was
that karaf .xml file that was supposed to handle this was incorrectly
located at `src/main/features/features.xml` but was supposed to be at
`src/main/feature/feature.xml` to work properly in Karaf 4.

Resolves: bug 8692

Change-Id: I9923a2b2598e05e95bb68a01cde5a8894679e534
Signed-off-by: Tomas Slusny <tomas.slusny@pantheon.tech>