No traceback when no cloudlets installed

Catch the `TypeError` generated when running `nepho cloudlet list` and
no cloudlets are installed.

Fixes #99.
Merge pull request #101 from huit/99-no_cloudlets_traceback

No traceback when no cloudlets installed
Merge remote-tracking branch 'upstream/master'
Fix cloudlet installation

`nepho cloudlet install <foo>` works now, and traps exceptions in the
event that an install fails.

Fixes #102.
Merge pull request #103 from huit/102-cloudlet_install_broken

Fix cloudlet installation
remove extraneous print statements and code from scenerio.
Merge remote-tracking branch 'upstream/master'