Fix for #315 (v2 Ethereum)

[eboadom]

Same exact changes as on https://github.com/aave/protocol-v2/pull/316 but to apply on the deployment of Aave v2 Ethereum.

Only non-solidity code was slightly adapted to the version of the repo from where this branch was created https://github.com/aave/protocol-v2/releases/tag/1.0, the same version as on the target branch https://github.com/aave/protocol-v2/tree/release/aave-v2-ethereum

[eboadom]

Gas report diff

As expected, slight increase on average in single actions (~1k gas), with the benefit appearing on multiple actions in the same timestamp, same block.

Before fix

After fix