Filecoin verifier tools

Javascript implementation of a HAMT using ipld

For now, just testing how this could be implemented, works for getting the verifiers and their info.

Files
* hash.js: simple implementation of murmur3 hash
* hamt.js: implements lookup and iterating HAMT tries
* methods.js: has the following methods
* signTx: gets the nonce from RPC and signs a transaction
* sendTx: same as above, but also sends the transaction
* decode: decodes data from raw format
* encode: encoding the data
* actor: convenience for encoding actor info

Samples
* add-client.js: adds a new verified client with cap
* approve-verifer.js: approve adding a verifier in multisig
* propose-verifier.js: propose adding a verifier in multisig
* index-transaction.js: add transactions from blocks to postgres
* tx-server.js: serve a list of transactions from postgres
* tx-client.js: get a list of transactions and parse parameters
* multisig.js: show multisig info
* verified.js: list verified clients
* verifiers.js: list verifiers
* info-browser.js and test.html: check that everything works in browser