Slack + Static assets in routes

[Evan Tahler]

https://github.com/evantahler/actionhero/releases/tag/v13.4.0

Community -> Slack

• We now use slack for the Actionhero community, and have shut-down our old Gitter room.
• Anyone can join our new Slack team... please do! Visit slack.actionherojs.com to get started!

Map static folders in routes.js

You can now map a folder like this:

get: [
  { path: '/my/special/folder', dir: __dirname + '/../my/special/folder', matchTrailingPathParts: true }
],

and access all files under the given "dir" path within the mapped path.

• by @S3bb1 via #826

Misc

• We now test on node versions 4,5, and 6 on Travis.ci. Actionhero works on them all! Yay!
• Under the hood cleanup to use the async package more (clean up some gnarly old looping code)
• Under the hood cleanup to use "error" rather than "err" for clarity
• Primus updated to v5.2.1