Get `list` of installed packages:

  $ STOW_PATH=~/Desktop/test-stow-manager $TESTDIR/../bin/stow list
  No linked packages found.
  [1]

Get `list` of installed packages:

  $ STOW_PATH=$TESTDIR/tmp $TESTDIR/../bin/stow list
  No linked packages found.
  [1]

Set STOW_PATH to TESTDIR/tmp folder
Set STOW_PATH to TESTDIR/tmp folder
