drop Node.js v0.10 and v0.12 support

[boneskull]

We can no longer run our development environment on node.js v0.10/v0.12 (see request/request#2772) without adding a npm-shrinkwrap.json or doing other high-effort/low-reward things to work around this.

furthermore, it's making it more difficult to apply security fixes. at least one of these Node.js versions (v0.10) has known vulnerabilities which have gone unpatched (in an official capacity).

we should not continue to supply updates for these environments.

• remove 0.10, 0.12, iojs & 5 from .travis-ci.yml and appveyor.yml
• update engines field in package.json
• necessary security upgrades (this includes debug and growl)
• upgrade anything else we can get away with (stick to dev deps)

To be clear, Mocha still runs in Node.js v0.10 and v0.12; you just can't clone a working copy and run the test suite.

[boneskull]

also dump iojs because

[boneskull]

also Node.js v5 is no longer maintained, so drop that too.

[ScottFreeCode]

This week is the week we will merge as many semver-major updates as we can?

[boneskull]

sure. I'll try to release EOD Fri to give people the weekend to find whatever we broke.

[boneskull]

WIP PR: #3017

[boneskull]

@ScottFreeCode please throw stuff into kanban if you want to see it land

[ScottFreeCode]

Will do; gotta turn in for the night but can focus on it tomorrow so we have the middle of the week to evaluate stuff.

[boneskull]

closed via e39a867