Update to Truffle 4.1.5 and Ganache 6.1.0 (#876)

* Update to ganache-cli v6.1.0 and truffle v4.1.0

* Update to stable version of ganache-cli

* fix: update event emission warning

- Fix event emission warnings for solidity 4.21 after truffle has been
updated to use this version

* fix pr review comments

* update to truffle v4.1.5

* update package-lock

* add additional emit keywords

* update solidity-coverage to 0.4.15

* update to solium 1.1.6

* fix MerkleProof coverage analysis by testing through wrapper

* change version pragma to ^0.4.21

* fix solium linting errors

test/helpers/expectThrow.js

@@ -8,7 +8,7 @@ export default async promise => {
     // TODO: When we contract A calls contract B, and B throws, instead
     //       of an 'invalid jump', we get an 'out of gas' error. How do
     //       we distinguish this from an actual out of gas event? (The
-    //       testrpc log actually show an 'invalid jump' event.)
+    //       ganache log actually show an 'invalid jump' event.)
     const outOfGas = error.message.search('out of gas') >= 0;
     const revert = error.message.search('revert') >= 0;
     assert(