Improvements for connection logic and error handling

[cdheiser]

As noted in #120 some users are having issues with this code connecting properly and locking up home assistant. 3 main changes here:

1. Better exception handling so it's clear if we're strugging on the login vs. password vs. waiting for the prompt
2. await with timeouts for the login and password prompts so we don't lock up home assistant
3. Drain the writer before we wait for a new prompt.