Add memcache implementation of cache (#1848)

cache/cache.go

@@ -1,6 +1,7 @@
 // Package cache is a caching interface
 package cache
 
+// Cache is an interface for caching
 type Cache interface {
 	// Initialise options
 	Init(...Option) error
@@ -14,6 +15,15 @@ type Cache interface {
 	String() string
 }
 
-type Options struct{}
+type Options struct {
+	Nodes []string
+}
 
 type Option func(o *Options)
+
+// Nodes sets the nodes for the cache
+func Nodes(v ...string) Option {
+	return func(o *Options) {
+		o.Nodes = v
+	}
+}