check tap.yml gem configurations on gem

A configuration error results when a gem is installed with a tap.yml that specifies uninstalled gems. Obviously the best solution is to make the installed gem specify the other gems as dependencies. Add a rake task to execute before :gem to check:

task :check_tap_configuration do
  if File.exists?("tap.yml")
    require 'yaml'
    if (hash = YAML.load_file("tap.yml")).kind_of?(Hash)
      gemspec.dependencies.collect {|d| d.name }
      ...
    end
  end
end

task :gem => [:check_tap_configuration]