Drop lodash

`wait-on` was created in the early days of Node.js development. Now with ES6 and new ECMAScript and Node.js features, many lodash methods usages are no longer needed.

If you wish, I can start progressive migrating, this should further reduce installation size of the package.

Currently, `wait-on` is the only dependency in my project that uses `lodash`.

Start by locating the lodash usages and the dependency declaration in the wait-on repository, then run the existing test suite to establish current behavior. Replace the unnecessary usages while preserving command-line and Node.js API behavior; done means the tests pass and lodash is no longer an installed dependency.

Written by the indexing model from the issue text.