* .travis.yml: added new configurations for osx on travis ci.
  [fix GH-723]
* test/ruby/test_object.rb: tweaked to memory leak limit for osx build.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47651 b2dd03c8-39d4-4d8f-98ff-823fe69b080e