table_exists should be called aggresively while it is false or nil, to avoid bootstrapping issues

don't test 1.9.3 in travis, it blows up randomly due to incorrect implementation of weak refs in 1.9.3

.travis.yml

@@ -1,6 +1,5 @@
 language: ruby
 rvm:
-  - 1.9.3
   - 2.0.0
 before_script:
   - cp config/database.yml.development-sample config/database.yml