Rename keychain#(token|password) -> github_(token|password).

Also rename creds.rb -> github_creds.rb
Add apple id and password to the keychain and config.
Here's a preflight check to collect and verify app store credentials.

It uses mechanize to verify by logging into appleid.apple.com.
Mechanize requires nokogiri, which we limit to < 1.6 for ruby 1.8.