Fixed dev dependencies in composer.json

Since jms/translation-bundle is only working with sf 2.2 from
version 1.1.x-dev, I updated the composer.json file to add the
@dev flag to the translation bundle version definition.

Now the --dev requirements can be isntalled again.
Implemented ConstraintValidator::validate()

Since version 2.1 of symfony/validator, ConstraintValidator::isValid()
is deprecated an triggers an E_DEPRECATED error.

Unfortunately the error handling in some circumstances triggers
SIGSEGV in PHP-FPM (I havn't been able to pinpoint the exact cause).

Now isValid() is just a BC wrapper for validate() not triggering any
errors.
Fix ukrainian translation
Merge branch 'fixuktranslation'
added some missing translations
Update composer.json
Merge pull request #1346 from ehsan89/patch-2

added some missing translations
Merge pull request #1301 from spolischook/master

Fix ukrainian translation
Merge pull request #1298 from tPl0ch/hotfix/composer-dev-requirements

Fixed dev dependencies in composer.json
Merge pull request #1299 from tPl0ch/hotfix/constraint-validator-deprecated

Implemented ConstraintValidator::validate()