Activation, importKey, and faucet/fundraiser support

New features

• Add activation operation support Tezos.tz.activate("pkh", "secret")
• High-level function to import a key Tezos.importKey("your_key")
• Utility to retrieve private key from faucet/fundraiser account
• Add RPC support for backing related endpoint (endorsing rights/baking rights)
• Add RPC support for voting endpoint

Fixes

• Bugfix in michelson-encoder packages and more tests

Other

• We now have documentation website managed from the tezos-ts repo
• We added an integration tests suite that will be run regularly against RPC servers to detect breaking upstream changes