Complete Describe Workbench Spec

Update Framework requirement, v3.13.2
Update shared describe context
- Remove 'add line' step from title & author search.
  (No longer necessary as of 1.5.0-M2-r18177, 2014/03/26.)
Add instance/holdings call number search
Update holdings search
Use holdings call number search method in spec/describe/shared.rb
- Look for a non-readonly field in holdings call number check
- Look for a non-readonly field in item barcode check
Add barcode search to describe shared
Use item barcode search