Porting to solidity v. 0.5.0

[gigatesseract]

No description provided.

[pathakcodes]

Nice work !! Your PR helped me lot with V 0.5.0 .Thanks n keep the good work.

[gigatesseract]

Thank you! :) @pathakcodes
@gwmccubbin Can you merge/suggest changes in this PR?

[joshuacox]

This probably should have been merged in long ago?

For what it's worth I ended up coming to pretty much the same changes in my own upgrades. Though it seems to me that the build directory should be ignored in addition to the node_modules.

[joshuacox]

why is the .gitignore file ignoring itself?

[joshuacox]

And it seems the build directory should be ignored?

[camerenisonfire]

In case someone is running into the same issue I am having of using Solidity ^0.5.0 and getting TypeError that msg.sender is not implicitly convertible to expected type uint256:

You need to wrap msg.sender in unit256(). For example, voters[uint256(msg.sender)] = true;