Load fixtures from linked folders
Merge pull request #11765 from kassio/load-fixtures-from-linked-folder

Load fixtures from linked folder
Make `rake doc:guides` works again.  Fix #10384.

Conflicts:
	railties/guides/rails_guides.rb
	railties/lib/rails/tasks/documentation.rake
Fix test incompatible with 1.8.7
Merge pull request #11930 from UncleGene/ties_test

Fix test incompatible with 1.8.7
Fix 1.8.7 incompatible respond_to_missing