Quoted ENV variables used to work in 0.2.? and broke with 0.3.0.

.travis.yml as per documentation:

language: php
php:
- 5.5
env:
 - LOGIN='secret'
script:
 - echo $LOGIN

Expected output: secret (no quotes)
Actual output: 'secret' (including quotes)

This will now pass the following instruction to Docker:

ENV LOGIN 'secret'

The ENV instruction has two forms. The first form, ENV , will set a single variable to a value. The entire string after the first space will be treated as the - including characters such as spaces and quotes.

https://docs.docker.com/reference/builder/#env

For the reference, noticed this in one of my projects.