option to prevent default translation search

Fixes https://github.com/KnpLabs/DoctrineBehaviors/pull/107
Adding a test for Translatable

Adding a test to check the capacity to add a new language/value for an
existing translatable entity.
At the time of this commit, there is an issue as the test fails (all new
language/values are added to "en" language)
Merge remote-tracking branch 'derek-roth/patch-1' into fix/107-translations-v1
Test fix for translations.
Merge pull request #157 from kuczek/fix/107-translations-v1

Translation fallback