More idiomatic source layout

This is an attempt to make the source layout adhere to Go conventions,
for example outlined here:
  http://code.google.com/p/go-wiki/wiki/GithubCodeLayout

Basically, we can assume that people will name their packages using
`github.com/username/...` pattern and put the source files in the
root of repository. It is not desirable to force them to use
non-standard directory layout or change their `GOPATH` locally
to get the Shippable build to work.

To make the standard layout work on Shippable,  we need to link the
checked-out repository to `$GOPATH/src`, so it will be properly resolved
by Go tools. When testing the main package, we can use `./` as the package
name to avoid repetition. If we had multiple package tests, we could use
`./...`.

BTW, I couldn't get `gocover-cobertura` nor `gocov-xml` to output
anything more interesting than '0' as line or branch coverage. I guess
this is a problem with current versions of these tools.

Also, modified slightly the test suite file, so the path to the test
results location is taken from an environment variable.
Merge pull request #1 from anowak/new-layout

More idiomatic source layout