CCNxTxRxRelay should allow selection of Internal or External storage for Repo content

[truedat101]

Currently, the repo defaults to using external storage to put content. We should add a preference option to allow selection of internal or external. We probably want to add a control panel to assist the user in making a decision:

• Available Internal storage
• Available external storage
• Write speed/read speed for both

I suspect that performance suffers on the external SD Card.

[truedat101]

Related to #1 . To me, if we don't address platform performance issues, we can't hope to use this in real world, non-academic applications.