[WIP] Upgrade to Truffle 4.0.0

[nberger]

Upgrades to solc 0.4.17 and truffle 4.0.0-beta.2

But perhaps we should wait until the final truffle 4.0.0 is released before merging this

@AugustoL, @cgewecke: thoughts?

[coveralls]

Coverage decreased (-0.6%) to 98.792% when pulling 386a0c7 on truffle-4.0 into 86d8429 on master.

[cgewecke]

@nberger Yeah! It works. Looks good.

There are a couple bugs at solidity-coverage we have to fix (today?) so that pure ,view and pragma experimental don't cause problems. But they only affect files imported from outside the contracts folder (pure, view) and yarn installations (pragma experimental).

[AugustoL]

Lets continue using solc 0.4.15, we dont want to upgrade and change the contracts again.

[nberger]

Ok, closing now then, thanks!