Add support for keypairs

Adds support for the following keypair operations:
- ListKeyPairs yields the list of available keypairs.
- CreateKeyPairs will create or generate a new keypair.
- DeleteKeyPair wil delete a keypair.
- ShowKeyPair will yield the named keypair.
diff --git a/interfaces.go b/interfaces.go
index c986fce..725b602 100644
--- a/interfaces.go
+++ b/interfaces.go
@@ -147,4 +147,18 @@
 	// ListFlavors yields the list of available system flavors.  This function
 	// returns full details for each flavor, if available.
 	ListFlavors() ([]Flavor, error)
+
+	// KeyPairs
+
+	// ListKeyPairs yields the list of available keypairs.
+	ListKeyPairs() ([]KeyPair, error)
+
+	// CreateKeyPairs will create or generate a new keypair.
+	CreateKeyPair(nkp NewKeyPair) (KeyPair, error)
+
+	// DeleteKeyPair wil delete a keypair.
+	DeleteKeyPair(name string) error
+
+	// ShowKeyPair will yield the named keypair.
+	ShowKeyPair(name string) (KeyPair, error)
 }