Updated HHVM role to reflect changes in HHVM [Precise64 only]

Note: This is my first attempt ever at contributing to anything on Github. I could not find a protocol for contributing, suggestions are more than welcome if I'm doing it wrong ;-)

When attempting to provision a Precise64 box with HHVM enabled from a Phansible-generated playbook, it exits because it cannot find the correct Boost version. This PR attempts to remedy this by adding the Boost PPA as suggested on the HHVM Github page [right here](https://github.com/facebook/hhvm/wiki/Prebuilt-packages-on-ubuntu-12.04)

As the current HHVM release is configured to listen on port 9000 by default, I have also removed the lines checking and changing the HHVM server configuration file. (it was also changed from a .hdf to a .ini extension)

I have tested the changes manually using a Phansible-generated Precise64 playbook. The Lucid and Precise32 ones are currently broken but that already seems to be the case before applying the changes in this PR.