Whitespace changes
Unified handling child processes

Unified handling child processes to a new Brackup::ProcManager. Components
of Brackup can now register handlers and return if they have recognised the
child waitpid returned.  Currently, these components are: GPG, Restore and
Target.  This solves the issue where GPGProcManager encountered an unknown
child, presumably a daemon used to upload data to an Amazon target.
Whitespace changes