Switch to Aptible Ubuntu base image and use apt-install (to incorporate apt-get update)

[fancyremarker]

This issue is intended to fix this bug when building the current Dockerfile:

E: Unable to locate package curl
 The command [/bin/sh -c sudo apt-get install -y curl] returned a non-zero code: 100

This error happens when the APT cache becomes stale, and it's necessary to run apt-get update before apt-get install [...] in order to avoid this.

I've switched to our quay.io/aptible/ubuntu:14.04 image out of habit, but an alternative approach would simply be to add:

RUN sudo apt-get update

before

RUN sudo apt-get install -y curl

[henrystewart]

Hey guys, it would be helpful to merge this. I ran into this issue just now.

[henrystewart]

@besquared