HHVM 3.2.0 and updated install procedure

- Added HHVM release 3.2.0 (fixes #14)
- Use bundled installer to install all necessary files (fixes #11)
- No longer install hhi files
- Added temporary dependency dev-db/sqlite
Use pkg_pretend to check the gcc_version

- Switch statement between releases and 9999
- 9999 should require "**" rather than "~amd64"