fixed error when trying to get root documents
also updated api to use uri over url
moved additional metadata to _meta attribute
Merge branch 'master' of github.com:KodaFramework/koda-ui

Conflicts:
	lib/koda-ui.rb
	spec/ui_spec.rb
created a hash that will select values from a nested hash using dot notation
example:

hash = Koda::UI::Hash.create({'a' => {'b' => 1}})
hash['a.b'] => 1
added method to parameterise collection retrieval