First install dependencies before trying to build an npm
Log known failures and don't fail the build on them.

We've had these fails for a long time now. They
still need to be fixed, but as it is not they cripple
the workflow for accepting Pull requests and not knowing if
they would cause regression without plowing through travis logs.

Fixing the current state of php.js known_failures.txt will make
the process of writing & accepting contributions easier, hopefully
raising the quality more than accepting these failures will hurt it.

The known failures still throw errors for everyone to see, they just
won't fail the build anymore