New Provider: Personal Testnet

Now that TestRPC can create a programmatic provider, we could bake a testrpc into MetaMask, and then MetaMask users could use a web IDE and client-side block explorer to have a very rich first experimental period with the blockchain.

Would've been really nice when leading workshops & hackathons, reduces a whole system dependency, and let me tell you, it wasn't fun running TestRPC on a class of old windows machines (waiting for the all-JS version).

No files, tests, or entry points are named. Start by reviewing MetaMask's existing provider architecture and how TestRPC could be embedded; define the scope for a personal testnet, including the web IDE and client-side block explorer described here. Done would require an agreed design and an implementation plan, not just a local edit.

Written by the indexing model from the issue text.