Simplified registry access, so that RegistryHandler can be used in place of the oddly named RegistryDefaultHandler
implementation.
RegistryDefaultHandler now delegates to a platform specific implementation of RegistryHandler,
if registry access is supported, or a no-op implementation of RegistryHandler if it isn't.
The RegistryDefaultHandler.getInstance() method is now deprecated.
Backed out RegistryDefaultHandler changes as they were pulling in classes from the com.coi.tools.os.win package
which are not included in the uninstaller on unix platforms
Merge pull request #89 from unb/master

Backed out RegistryDefaultHandler changes, but left in minor code cleanups