Backport test output upload

The tests we are running for the 1.4 releases do not contain the console output, which makes figuring out what actually broke a guessing game.

This is a straight cherry pick of two commits from master that output the test output to the log directory and upload the log file to Giddyup when the test runs.

I've tested it locally. You can see the uploaded artifact from my tests here:

http://giddyup.basho.com/#/projects/riak_ee/scorecards/106/106-201-verify_build_cluster-osx-64/59168/artifacts/1052651

I ran

./riak_test -c rtee -t verify_build_cluster -r config

with my configuration:

```
{platform, "osx-64"}
{giddyup_host, "giddyup.basho.com"}
{giddyup_user, "<user name here>"}
{giddyup_password, "<password here>"}
```