Make home URL optional and support dependencies (#260)

Signed-off-by: Reinhard Nägele <[email protected]>

etc/chart_schema.yaml

@@ -1,12 +1,13 @@
 name: str()
-home: str()
+home: str(required=False)
 version: str()
 apiVersion: str()
 appVersion: any(str(), num(), required=False)
 description: str()
 keywords: list(str(), required=False)
 sources: list(str(), required=False)
 maintainers: list(include('maintainer'), required=False)
+dependencies: list(include('dependency'), required=False)
 icon: str(required=False)
 engine: str(required=False)
 condition: str(required=False)
@@ -20,3 +21,17 @@ maintainer:
   name: str()
   email: str(required=False)
   url: str(required=False)
+---
+dependency:
+  name: str()
+  version: str()
+  repository: str()
+  condition: str(required=False)
+  tags: list(str(), required=False)
+  enabled: bool(required=False)
+  import-values: any(list(str()), list(include('import-value')), required=False)
+  alias: str(required=False)
+---
+import-value:
+  child: str()
+  parent: str()