Add basic Travis CI configuration

I added a basic Travis CI configuration to make the build status more
transparent. I added a small logo to the bottom of the README with the
status and a link to the build.

@evancz after merging this you'd have to go to https://travis-ci.org
and enable the build for this project, just takes a couple of clicks.
See http://about.travis-ci.org/docs/user/getting-started/.

I tested this on my own github account and the configuration worked
(ie, it showed the same build errors on Travis that I'm experiencing
locally).
Add the always function

I want it, I do not want to rename constant, and I think it is a good
name.
resolve conflict in README!
Merge branch 'jsl-add_travis' into dev
Get rid of the word "simply". It is a condescending word.
Move build status higher up
Add a test for port parsing and types

Partly addressing #442