Fix data URI decoding in CordovaResourceApi

It was not URI-decoding first, and so was broken for non-base64-encoded
URIs.
Use a higher threshold for slow exec() warnings when debugger is attached.
Log WebView IOExceptions only when they are not 404s
[CB-4495] Modify start-emulator script to exit immediately on a fatal emulator error.
Tweak the online bridge to not send excess online events.

It does so by having the JS tell it when online events have fired.
[CB-3542] rewrote cli tooling scripts in node