Travis tests previous amplifier

[generalhenry]

Currently my build is failing on travis: https://travis-ci.org/appcelerator/amp/builds/178074710

This is due to a initialization bug introduced by #479

I'm working on a fix to the initialization bug, but the issue will still remain that amp pf pull && amp pf start pulls and starts amplifier from docker hub.

[generalhenry]

@bquenin I fixed the init bug and hot pushed to docker hub to work around the prev build issue. I see your work in https://github.com/appcelerator/amp/tree/amp-tests-fix which looks like you're making headway.

My current thinking is:
./shrink local
amp platform pull --local
amp platform start --local
Which would build the amp image locally, skip pulling amp and then launch services with the local amp image.

[bquenin]

You're right, I was working on a fix, but yours is better.
I'll submit a pull request with a doc for local test development.