Allow to run on read only root fs

In order to be able to run on read only root fs, two changes have been
done:

* unpack tomcat war at container creation
* launch the property file configuration conditionnally

If "ON_KUBERNETES" environment variable is set to "TRUE" (default is
"FALSE" for backward compatibility), the proper have to be set at boot
via configmap on Kubernetes for example.

Changes are backward compatible and shouldn't change actual behavior per
default.

Issue-ID: VID-850
Signed-off-by: Sylvain Desbureaux <sylvain.desbureaux@orange.com>
Change-Id: I6f96e2ca55093ee899be18d6ce4c2dfd7c1a5792