Display prepare_command stdout during pod install

This change adds in the display of the `bash` subprocess's `stdout` to the pod process's `stdout`. There are a number of situations where this would be considered desirable:

* Give the user some information about which operations were preformed during the install
* Give the user information about recoverable (or non-critical) errors which occurred
* Give the user warnings, recommendations, or other helpful information

In particular, this feature is critical for any `prepare_command` which calls to a command which should **not** have its output suppressed, such as tools which need to show data even on an exit code of 0 - or the usage of *poorly written* tools which fail but return an exit code of 0 anyway.