New Features
- `yotta start` command (aka `yotta run`) to launch the built program (requires target support)
- Support for additional scripting hooks, including post-install, post-build and pre-publish hooks. See the [docs](http://yottadocs.mbed.com/reference/module.htmlscripts) for more info.
Other Improvements
- Depend on an up-to-date version of [certifi](https://pypi.python.org/pypi/certifi), which includes support for the registry's new SSL certificate.
- Update the required versions of dependencies
- Fix an issue that prevented subdirectories from being used in the `lib` or `bin` properties in module.json
- `yotta debug` (and the new `yotta start`) now choose a sensible default program to launch, instead of failing when none is specified.