feat: remove yarn in favor of npm

fix: make SplitPayment payable by default

Address new compiler warnings

Minor formatting change

Update to truffle 4.0.0 and solc 0.4.18

This is required to update to truffle 4 and solc 0.4.18, see PR #573

had to up the gasLimit in test.sh to avoid an out of gas error when deploying the scripts

Create CappedToken, a capped MintableToken

Small code style change

Fix unused variable warning in `Standard Token.sol`

Replace deprecated throw with assert in Solidity tests

http://solidity.readthedocs.io/en/develop/style-guide.html#other-recommendations
The visibility modifiers for a function should come before any custom modifiers.

Add npm init in README

Make coverage badge flat

added versions output to Travis CI log #534

Do not notify via Slack about PR build failures

fix docs issue #459 and align with README.md