Add vendor files for spf13/viper

vendor/github.com/xordataexchange/crypt/backend/backend.go

@@ -0,0 +1,32 @@
+// Package backend provides the K/V store interface for crypt backends.
+package backend
+
+// Response represents a response from a backend store.
+type Response struct {
+	Value []byte
+	Error error
+}
+
+// KVPair holds both a key and value when reading a list.
+type KVPair struct {
+	Key   string
+	Value []byte
+}
+
+type KVPairs []*KVPair
+
+// A Store is a K/V store backend that retrieves and sets, and monitors
+// data in a K/V store.
+type Store interface {
+	// Get retrieves a value from a K/V store for the provided key.
+	Get(key string) ([]byte, error)
+
+	// List retrieves all keys and values under a provided key.
+	List(key string) (KVPairs, error)
+
+	// Set sets the provided key to value.
+	Set(key string, value []byte) error
+
+	// Watch monitors a K/V store for changes to key.
+	Watch(key string, stop chan bool) <-chan *Response
+}