Ensure that WardenError#inspect does not leak info

Signed-off-by: Phan Le <ple@pivotallabs.com>
Log when staging fails

Signed-off-by: Phan Le <ple@pivotallabs.com>
Fix quotes

Signed-off-by: Phan Le <ple@pivotallabs.com>
Stop using custom logger

  * rely on seno instead

Signed-off-by: Phan Le <ple@pivotallabs.com>
Remove unnecessary class hierarchy

Signed-off-by: Phan Le <ple@pivotallabs.com>