util: Add HomePath helper

This returns home path correctly on both Windows and Linux.

Signed-off-by: Asias He <asias@cloudius-systems.com>
util: Add ID helper

Generate an ID based on time.

Signed-off-by: Asias He <asias@cloudius-systems.com>
vmw: Add StopVM method

This is used to stop an Instance.

Signed-off-by: Asias He <asias@cloudius-systems.com>
vbox: Add StopVM method

This is used to stop an Instance.

Signed-off-by: Asias He <asias@cloudius-systems.com>
qemu: Redirect monitor to unix socket instead of stdio

We can use this socket to control qemu instance, e.g. stop an instance.

Signed-off-by: Asias He <asias@cloudius-systems.com>
qemu: Add StopVM method

This is used to stop an Instance.

Signed-off-by: Asias He <asias@cloudius-systems.com>
stop: Add capstan stop cmd

`capstan stop` will stop an instance while keeping the root disk of the
instance undeleted.
Merge pull request #58 from asias/stop

Add capstan stop cmd