Draft: Remove normalization of failed transactions
From @tbinetruy search, we can get the status of the tx by the receipt. But each time we access the tx receipt we request the node. This PR will add a _receipt
field on the EthereumTransaction Model, and will modify the property to get the data from the db if it exists.
It will also modify the index_level
function of the EthereumProvider to filter out failed txs and not index them.
Closes #19