Upgrade test suite, rails 4 compatible with all tests passing

Hello,
I have updated the test suite based on the test suite at https://github.com/svenfuchs/i18n

Then, failing tests revealed some bugs that I have also addressed about missing translations not being stored and on the StoreProc feature not working at all.

For the StoreProc tests to work, a modification on the i18n test have to be made. I am sending a pull request there to apply the change.