document sample node transaction

update package json

Update Readme.md

modify node sample for cth selftx

add tx balance pre check - verify minimum balance

update default configs - use eth mainnet as default RPC - add xdai and cth as optional chains

update web3 and bitcoinjs-lib

Update eth-keychain-example-node.js

add screenshot

add some documentation on test helpers and gas costs, the nice thing about this gas cost is that is fixed to usd on xdai

fix send error :lol:

fix send error :lol:

browser hook

update configs with instructions on how to run a node

browser version working as well