[Bug] `rename` command does not rename file , just the json value

[pspiagicw]

Currently the rename commnd does change the name of the machine , but
it does not change the file name. This means this sequence of events can be deadly

• You create a machine with name "Machine 1" , it names the file machine_1.json
• You rename that machine to "Machine 2" , now the file machine_1 has name Machine 2.
  That means now "Machine 1" does not exist but "Machine 2" exists.
• You create a machine with name "Machine 1".
• You list number of machines , and it only lists "Machine 1" , "Machine 2" was overwritten!