version 0.5.0

Implement Subline Object, Lookup Page as new base classes.  Implement
Requisition, Vendor Lookup, and Building Lookup pages in OLEFS.  Add
line objects and subline objects to requisition to handle line items
and related sublines/tabs.  Implement YARD documentation, 100% coverage.
Rename main class, OLE_QAF::OLE_Framework -> OLE_QAF::Framework.
Add create_requisition and update Readme in examples/ directory.