Fixed simulator error alerts, made cursor always hide, updated readme

Hey loren!

Huge fan of your work for the iOS community - thanks for doing tweetie, letterpress, pull to refresh & all the other cool stuff you've done.

Just fixed a few things in SimFinger:

- Removed cursor from ever being shown (before, it was shown on the first click)
- Removed annoying popup, because of attempt to open simulator again.
- Added steps on how to use
- Updated readme