Support cascading hst:configuration inheritance

+ hst:hst
   + hst:configurations
      + common
      + corporate
          - hst:inheritsfrom = ../common
          + hst:sitemenus
          + hst:workspace
              + hst:sitemenus
      + subsite 
          - hst:inheritsfrom = ../corporate

for (String inheritPath : inherits) {
                if (!inheritPath.startsWith("../")) {
                    log.warn("hst:inheritsfrom property must start with ../ but this is not the case for '{}'. We skip this inherit", configurationRootNode.getValueProvider().getPath());
                    continue;
                }
                String hstConfigsInheritedRelPath = inheritPath.substring(3);

                String absHstConfigsInheritedPath = configurationsNode.getValueProvider().getPath() + "/" + hstConfigsInheritedRelPath;
                // regardless whether absHstConfigsInheritedPath exists or not, add it to the compositeConfigurationDependencyPaths : If it gets
                // added later on, it does impact this CompositeConfigurationNodes
                compositeConfigurationDependenyPaths.add(absHstConfigsInheritedPath);
                compositeConfigurationDependenyPaths.addAll(createDependencyPaths(absHstConfigsInheritedPath, relPaths, false));
                HstNode inheritConfig = configurationsNode.getNode(hstConfigsInheritedRelPath);
                if (inheritConfig != null && isValidInheritedNode(inheritConfig)) {
                    orderedRootConfigurationNodeInheritanceList.add(inheritConfig);
                    if (inheritConfig.getValueProvider().hasProperty(HstNodeTypes.GENERAL_PROPERTY_INHERITS_FROM)) {
                        log.warn("Skipping inheritfrom property for configuration node '{}' because this node is already inherit. Not allowed to inherit again", inheritConfig.getValueProvider().getPath());
                    }
                } else {
                    log.error("Relative inherit path '{}' for node '{}' does not point to a node of type '{}' or does not exist. Fix this path.",
                            new String[]{inheritPath, configurationRootNode.getValueProvider().getPath(), NODETYPE_HST_CONFIGURATION});
                }
            }

if (inheritConfig.getValueProvider().hasProperty(HstNodeTypes.GENERAL_PROPERTY_INHERITS_FROM)) {