oscm-birt: Add ability to unpack user provided report templates

[shimizuf]

From servicecatalog/oscm/issues/41

The reporting container needs functionality to import and serve user provided archive files with custom report templates. Enhance the oscm-birt startup script to find and unpack archives with report templates into the Tomcat directories so that they are available automatically, in addition to the standard templates. This should work similar to the functionality of oscm-branding and oscm-help.