Compile with no errors on the Solidity nightly builds

[nventuro]

There's a couple things missing for our code to be 0.5.0 compliant (see #1144 and #1068 for some related PRs): we should get those done to make sure we won't need to do any big changes once 0.5.0 is realesed.

[nventuro]

Due to some breaking changes, this may end up not being possible. See this thread for some relevant information.

[nventuro]

As a stepping stone, this changes should first go into the solc-nightly branch.

[nventuro]

master now compiles nighly as of e5b94c1