main: init: handle spaces in mount suggestion message
main: init: handle spaces in mount suggestion message

Before:
	You can now mount it using: gocryptfs a x MOUNTPOINT

After:
	You can now mount it using: gocryptfs "a x" MOUNTPOINT

This is still not bulletproof but should handle the common
case of having a space in the directory name. After all,
it's only a suggestion.

davesteele/gocryptfs,davesteele/gocryptfs,rfjakob/gocryptfs,rfjakob/gocryptfs,rfjakob/gocryptfs,davesteele/gocryptfs,rfjakob/gocryptfs