Add ConnectivityMonitor, Robolectric, Snackbar

Created by: lispyclouds

Changed:

• Add a connectivity monitor which notifies subscribers of network change
• Add Robolectric framework to ease out Unit Tests
• Add Snackbar to display semi-important notices
• Add tests

This can be used as follows:

• In any Fragment, inject as follows:

@Inject lateinit var connectivityMonitor: ConnectivityMonitor

• Register callbacks (for example showing snackbars) as follows:

connectivityMonitor.subscribe { connected ->
    if (connected) {
        showSnackMessage("Network Connected.", Snackbar.LENGTH_SHORT)
    } else {
        showSnackMessage("Network Disconnected!", Snackbar.LENGTH_SHORT)
    }
}