chore: update dependencies

[wesleycho]

• Update dependencies as part of process to drop support for versions of Node.js below 4

Closes #1812
Closes #2688

[wesleycho]

I had to make a couple of changes for the upgrade.

The sinon changes were because sinon deprecated the fake call api from within stub.
The eslint package additions were caused by the upgrade of the eslint standard plugin, which required those packages to have to be installed in order to lint - those also resulted in having to make the minor linting change adjustments.
file-list.spec.js has a few hacky changes to defer checking until after the _.defer calls are able to do their job inside file-list.js.

There is still one test that eludes me currently.

[wesleycho]

This PR passes all CI checks except for Node 0.10 and 0.12 - it requires #2692 in order to properly pass.

[dignifiedquire]

Before we can merge & publish this, the following needs to happen

• remove lodash from helper export, so plugins can't use it anymore: https://github.com/karma-runner/karma/blob/master/lib/helper.js#L171
• go through all plugins in the karma-runner org and make sure they do depend on their own lodash version.

[wesleycho]

I just went through every repository - I believe we should be good, but you may want to do a second pass.

I also removed lodash from being exported.