Move zend xsl test from flaky to bad

Summary: It's legitimately failing

Reviewed By: @LiraNuna

Differential Revision: D1471013
Expose extension API version in output of 'hhvm --version'

Summary: It's useful for packaging and configuration management scripts that want to
determine where dynamic extension files should be placed.

Closes https://github.com/facebook/hhvm/pull/3322

Reviewed By: sgolemon, ptarjan

Differential Revision: D1469518

Pulled By: svcscm