bozo uninstall fails if configuration file is not found

[lukesmith]

Try running the following command when a configuration file "bozorc.rb" does not exist.

bozo uninstall

The following error is raised

#<Errno::ENOENT: No such file of directory - bozorc.rb

[gshutler]

Not sure there is a way of avoiding this as a configuration file may specify specific uninstall steps. However, we could make it produce a nicer error such as "no configuration file could be found, create one at [path] and add any configuration necessary".