fixed issue where personality wasn't working in request w/ config_drive (#213)

diff --git a/openstack/compute/v2/servers/requests.go b/openstack/compute/v2/servers/requests.go
index 0ec5b0f..c79a6e6 100644
--- a/openstack/compute/v2/servers/requests.go
+++ b/openstack/compute/v2/servers/requests.go
@@ -160,7 +160,7 @@
 
 	// Personality includes files to inject into the server at launch.
 	// Create will base64-encode file contents for you.
-	Personality Personality `json:"-"`
+	Personality Personality `json:"personality,omitempty"`
 
 	// ConfigDrive enables metadata injection through a configuration drive.
 	ConfigDrive *bool `json:"config_drive,omitempty"`