test transaction propagation

[heikoheiko]

scenario:
client creates a and broadcasts a transaction

assertion:
all clients should receive the tx within a limited amount of time.

[heikoheiko]

work in progress:
https://github.com/ethereum/system-testing/blob/master/scenarios/scenario_tx_propagation.py

todo scripting:

• switch to jsonrpc
• select node which mined a block and as a balance at coinbase to pay for the tx:

[heikoheiko]

depends on #53

[heikoheiko]

updated to use jsonrpc, fixed log event pattern
ready to go

[heikoheiko]

depends on #54