Put step-specific config in those steps [#61]

This is just something that's been bugging me for a while--they're
specific to Lint and Upgrade, so that's where they belong.

internal/run/config.go

@@ -6,11 +6,8 @@ import (
 
 // Config contains configuration applicable to all helm commands
 type Config struct {
-	Debug        bool
-	Values       string
-	StringValues string
-	ValuesFiles  []string
-	Namespace    string
-	Stdout       io.Writer
-	Stderr       io.Writer
+	Debug     bool
+	Namespace string
+	Stdout    io.Writer
+	Stderr    io.Writer
 }