Fixes for broken Transaction.addOutputs on testnet and testnet p2sh address parsing

* Fixes address.js to be able to deal with testnet P2SH addresses
* Enhanced address.js testsuite...now also verifies address versions
* Enhances README to show how to run test suite

Updated test suite should all pass.

(note that message signing is still broken on testnet, from my issue post...I wasn't able to deep dive into it :/...didn't appear to be anything super trivial)