Add where_object query to PaperTrail::Version.
Tweak Serializer :where_object_condition method tests so they check the argument syntax instead of the SQL

SQL matching was not working properly with all of the different versions of ActiveRecord and
different database adapters we are testing against on Travis, so this is a better gauge of what
queries are actually being generated by these methods.
Fix PaperTrail::Version#where_object so it works on Ruby19 and Ruby18
Convert tests for VersionConcern#where_object to RSpec specs and update tests to actually test for functionality
Merge branch 'where_object_method'; close #377
Update CHANGELOG for #380 and #377 [ci skip]