Add changelog entry for scaffold generator and jbuilder changes

Introduced in 3bfd99defb559af0b017ee920ca714aa1e367fdd.
Related to #8840.

[ci skip]
remove_possible_method -> remove_method

  Date#to_time and Date#xmlschema methods defined in Ruby 1.9.3
Merge pull request #8896 from NARKOZ/patch-5

remove_possible_method -> remove_method