CDI extension tests failing after upgrading to TestNG 6.7

After integrating ISPN-2450 the CDI extension test suite fails.
This is because weld and arquillian rely on certain sl4j and testng versions.
Rolling these versions back solved the problem:

      <version.slf4j.weld>1.5.10</version.slf4j.weld>
      <version.testng.arquillian>5.14.10</version.testng.arquillian>