Update TRAVIS CI to add coveralls

[cdrage]

Updates travis to enable coveralls support.

Fixes #281

[sebgoa]

I have access to coveralls via incubator. I will test this today.

[sebgoa]

that should be good.

You can add the badge to the README:

[![Coverage Status](https://coveralls.io/repos/github/kubernetes-incubator/kompose/badge.svg?branch=master)](https://coveralls.io/github/kubernetes-incubator/kompose?branch=master)

[cdrage]

@sebgoa done. now let's see if these tests pass :)

[cdrage]

Currently this isn't working for some odd-reason (timing out). I'll be looking at an alternative fix.

[sebgoa]

ok, I am going to merge it and fix it

[kadel]

Why merge it if its not working?
It looks like it is missing token https://coveralls.zendesk.com/hc/en-us/articles/201342809-Go

[sebgoa]

because I was tired of seeing this PR pending and seeing our code coverage on the front page will be good motivation to improve unit tests.

afaik, you don't need a token for public repos...

but yeah it is failing.

[kadel]

To be honestly I don't see reason why it couldn't be fixed in this PR.

Now front page shows no coverage and failed tests.

I've done some digging around, and it is timeouting because it runs all unit test again for every package as separate go test run.
like this:

for package in all_packages:
   go test package

it takes a long time to start go test and travis-ci jobs has 15min timeout.

Root cause for this is that for some reason go test can't collect coverage profile for multiple packages.
So you have to run it for every package again :-(

We could run tests and collect all coverageprofiles into one file and than call goveralls with -coverprofile to only submit results to coveralls.io as described here https://gist.github.com/rjeczalik/6f01430e8554bf59b88e

But it still requires to run go test for every package separately.

[kadel]

this is how kubernetes is dealing with this https://github.com/kubernetes/kubernetes/blob/master/hack/make-rules/test.sh#L228