Fix grammar mistakes

We were using every article possible with word "repository" in the
output of capstan -h:

   push		push an image to a repository
   pull		pull an image to the repository
   rmi		delete an image from an repository

Also, it should be "pull ... from". I consulted this with Don.
Merge pull request #52 from tgrabiec/fixes

Fix grammar mistakes
vmw: Support VMware Worksation on Windows

Tested on VMWare Worksation on Windows/Linux and VMware Fusion on Mac

Note: VMware Player does not contain vmrun which required by capstan, so
we do not support VMware Player.

Fixes #53.

Signed-off-by: Asias He <asias@cloudius-systems.com>
Use os.MkdirAll instead of mkdir to crate a directory

This works on all platforms.

Signed-off-by: Asias He <asias@cloudius-systems.com>
repository: Make it work on Windows

Later we should create a helper to copy a file using native golang.

Signed-off-by: Asias He <asias@cloudius-systems.com>
instance: Initial support

Add 'capstan instances' command to list all the instances started by
capstan. It looks like:

$ capstan instances
Name                 Platform   Status     Image
i1396582979          qemu       Running
i1396582986          qemu       Running
i1396582636          vmw        Running
i1396582975          vmw        Running

Signed-off-by: Asias He <asias@cloudius-systems.com>
Merge pull request #54 from asias/vmw

vmw: Support VMware Worksation on Windows
Merge pull request #55 from asias/win

Win
Merge pull request #56 from asias/instance

Instance
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
util: Add Connect helper

Connect works on both unix socket and windows named pipe

Signed-off-by: Asias He <asias@cloudius-systems.com>
instance: Move instance.go under cmd package

All the capstan cmd is under the cmd package. Move it to the right
place.
Merge pull request #59 from asias/cleanup

Cleanup