Feature/versioning 2

This PR add versioning to wallet storage and networking. In only check for Major version differences, as suggested in http://semver.org/

In the future, we can upgrade storage or add UX message in changes.
https://github.com/bitpay/copay/issues/372

Also this PR adapts Copay to use the new HierarchicalKey module name from  bitcore.

Fixes https://github.com/bitpay/copay/issues/375