tests/run: Add '-i' to tee invocations
tests/run: Add '-i' to tee invocations

This should avoid issues where we get EPIPEs in the destroy trap if
the listening tee dies.  For example [1,2]:

1. The script uses exec to insert a tee capturing future stdout and
   stderr before writing them to the original stdout and stderr.
2. The SIGINT comes in and all our sub-processes (including the tee)
   die.
3. The exit trap launches the destroy handler.
4. The destroy handler tries to write to stdout, which is now the pipe
   into that tee, but the tee is dead, so we get an EPIPE and the
   destroy callback exits before actually doing any cleanup.

With this commit, the tees will survive until the program feeding them
closes its side of the pipes, so we'll continue to have working
tee-managed output even after receiving a control-c.

The option is in POSIX [3], so this should be portable.

[1]: https://github.com/openshift/installer/pull/231#discussion_r217170257
[2]: https://gist.github.com/steveeJ/86efe22e8d2195f5d19efe05d03225b2
[3]: http://pubs.opengroup.org/onlinepubs/9699919799/utilities/tee.html

derekhiggins/installer,derekhiggins/installer