Fix gem source warning message.

The source :rubygems is deprecated because HTTP requests are insecure.
Please change your source to 'https://rubygems.org' if possible, or
'http://rubygems.org' if not.
Switch from Open4 to ChildProcess - Fixes #268
make channel-discover optional for custom channels
Merge pull request #436 from torrancew/bugfix/268

Switch from Open4 to ChildProcess - Fixes #268
- relax requirement
- version bump
- skip tests in cpanm build/configure dependencies too if requested.
- support Module::Build-style perl modules.
  This allows modules like Fennec to be packaged by fpm.
Merge pull request #441 from jordansissel/feature/cpan/ModuleBuild

- support Module::Build-style perl modules.
Merge pull request #438 from hatt/pear-discovery

make channel-discover optional for custom channels
Merge pull request #432 from mmb/gemsource

Fix gem source warning message.
- remove debugging
- work around missing features in ChildProcess
  This fixes previously-failing tests due to the Open4->ChildProcess
  patch.
- bump version
- update changelog
- purge perllocal.pod before packaging (#443)