Rename kite binary to kitectl and restructure the kite/cmd directory.

Lets be consistent against our -and with the rest of the world- tools and use `kitectl` instead of `kite`.

Kite package stays as is. Control applications name will be kitectl (like kloudctl and possible future fooctl's).
`github.com/koding/kite/cmd` package is also restructed for better readability. All subcommands resides in `kitectl/command` directory now.


I think that every command should have something like `NewRun()` or `NewShowkey` that returns a `cli.CommandFactory` type. We can move `ui` and `kiteClient` to a file called `default.go` with the names `DefaultUI` and `DefaultKiteClient`. 

This has the advantage that we put the logic for each command in their own file and doesn't clutter this file. otherwise if you add a new struct field to say `install`  you need to create the variable here and inject from here. With  time this is not going to be maintainable.