COOK-3107 - ZenPack provider uses old Zenpack source URL

[dpetzel]

Moving tracking of http://tickets.opscode.com/browse/COOK-3107 here.

The provider is hard coded to look for zenpacks at dev.zenoss.com This has two issues:

• Zenoss has moved to storing Zenpacks in other locations. dev.zenoss.com doesn't have any updated zenpacks
  • http://zenpacks.zenoss.com/pypi/
  • http://wiki.zenoss.org/download/zenpacks/
• This doesn't allow Zenoss installations behind a firewall without internet access to be able to install Zenpacks from an internal location