Reshuffle cloud-config

Read files cloud-config.d in alphanumeric order, then cloud-config.yml
`ros config` writes to cloud-config.yml (and cloud-config.d/private.yml - only private keys)

Add (c *CloudConfig) Save() method, use it to save the changed config

Read and apply metadata as part of LoadConfig()

Simplify ros config export logic

util/term.go

@@ -1,3 +1,5 @@
+// +build linux
+
 package util
 
 import "github.com/kless/term"