Failure to start LiveSync causes CLI to hang

The problem

Whenever starting LiveSync on a new project if LiveSync is unable to start (for example a TypeScript error is present) then CLI tries to exit, but hangs because it has child processes attached to it.

Steps to reproduce

On a Unix OS:

1. tns create myApp --tsc
2. cd myApp
3. echo asd >> app/app.ts // this will cause the transpile error
4. tns run android // could be ios just as well

At this point CLI fails to start LiveSync, because there is a syntax error in the main TypeScript file and the message Unable to apply changes on device: XXXXXXXXXXXXXX. Error is: TypeScript compiler failed with exit code 1. is displayed, however the process does not finish and the user is forced to break execution with Ctrl-C.

This issue is caused by the various child processes that CLI spawns like the one for communication with iOS devices or analytics.