properly indented authentication.wsdl
added :qualified and :singular to a type's element

:qualified - signals whether the element should be qualified
:singular - signals whether this element can occur more than once
grab namespaces from the definition and any schema

this does not include all namespaces, but it's more complete than
before and way faster than nokogiri's #collect_namespaces method.
refactored parse helper to care about the chrome
works-for-now detection for simple types
started adding support for simpleType elements
introduced the Operation object
fixed type-handling for anyType elements
removed Document#element_form_default

this value belongs to a certain schema, so we should handle it that way.
this breaks compatibility with savon, but let's assume we don't need
anyone to use this setting once we know all types.
removed Parser#document
refactored #target_namespace handling
refactored #namespaces
extracted code into Schema and SchemaCollection

instead of parsing the types, the Parser now creates a SchemaCollection
(which contains many Schema objects) which does the job. this change
should make it easier to deal with imports once we tackle that problem.
moved namespaces out of types

targetNamespace and elementFormDefault will stay with the schema
for now. we definitely need to know about this when resolving type
references, but right now we don't.
extracted operations out of the Parser
removed unused methods
removed shortcuts from Document
changed Wasabi from a module to a class

including the Wasabi module doesn't make much sense and changing the
library namespace to a class allows us to (later) simply instantiate
it and call methods instead of figuring out to use `Wasabi.document`.
sketched out the new interface
removed unused method