The next breaking version of mux.js

[brandonocasey]

1. Merge #361
2. Split classes into separate files in lib
3. Update all code in lib to es6 syntax
4. Update all code in test to es6 syntax
5. Turn the linter back on (see below) and fix issues
   a. remove the : from the front of the lint script in package.json b. remove the :from the front ofhusky.hooks.pre-commitinpackage.json`
6. Write proper dispose methods and use them when switching pipeline types
7. Verify that we dispose things correctly when we are done with them.