Reset preferences baseURI, rootURI, version when add-on was built by cfx.

Initialize myTitle from self.title or metadata.title when available.
2 of 2 tests pass when profile has turned e10s off, fails otherwise.
Built with cfx against sdk 1.17.
commit 09d9ebe2975774736275a069d589f81369f0b78d
Author: Adrian Aichner <adrian.aichner@gmail.com>