Dynamic bootstrap + minor changes

This replaces all the sysexec stuff in ios uiauto by a dynamic bootstrap allowing us to pass informations between the main node.js process and  the uiauto script at startup. The bootrap generator is [here](https://github.com/appium/appium-uiauto/blob/1.0.0-beta/lib/dynamic-bootstrap.js). In particular, this should fix all the appium app path issues.

The dynamic bootstrap is created in `${HOME}/Library/Application\ Support/appium/bootstrap', or in '/tmp/appium/bootstrap' if ${HOME} is not available. Md5 hashes are used to avoid creating too many bootstrap files. (In practise, there should be only one).

For the moment this using the following beta branches of appium-uiauto and appium-instruments:

- [appium-uiauto.1.0.0-beta](https://github.com/appium/appium-uiauto/tree/1.0.0-beta)
- [appium-instruments.1.0.0-beta](https://github.com/appium/appium-instruments/tree/1.0.0-beta)

Minor changes are mainly logging stuff.