Output all run.sh noise to stderr so that stdout is free.
Add tmpfile, passes, and fails commands to the test framework.
Fix enter-chroot -b error handling; resolves #439.
Add background tests.
Disable hung task timeout in edit-chroot as well.
Add `set -e` to all host scripts.

`-e` is critical for error handling in crouton: make sure the flag is
set even if the user forgets to add it on the command line.
Merge pull request #455 from drinkcat/set_e

Add `set -e` to all host scripts. Fixes #392.
Merge pull request #449 from drinkcat/edit-chroot-disablehungtask

Disable hung task timeout in edit-chroot as well.