separate server startup from init; add server kill method
add option to kill ADB synchronously
start/kill adb with 'subprocess' module to suppress stdout/stderr console window on Windows
move subprocess module to content directory for consistency with other modules
set 'ready' before notifying observers about ready state change
make ADB debug messages more consistent when used as CommonJS module
Merge pull request #5 from mykmelez/start-kill

separate server startup from init; add server kill method