Add publish to keg YAML

[rwxrob]

Each entry should be a description where this keg is pushed and how to get the current version of the keg. Multiple entries are expected. This is different than official URL, which may or may not actually be a method of acquiring the latest.

Entries must include the following types:

• HTTP
• SFTP
• RSYNC
• Git
• Physical location
• PO box
• Rhetorical procedure

Need to leave room for other methods eventually as well. But all need to be specified in the JSON schema for the keg file.

The type may or may not be something from which cache pulls can be automated.

Having multiple methods to get to a keg can be beneficial particularly for those behind firewalls and other problematic boundaries that can be shut down for any number of reasons. Using a rhetorical procedure can provide interesting ways to obtain the source that a non-initiate to a given KEG community would not understand --- by design. "Find me" could be an actual, valid entry. This is particularly compelling when realizing that any keg can be fully encrypted as well.