Refactored HHVM init.d and configuration

- Refactored init.d-script
- Added command configtest to init.d-script
- Many settings are loaded from conf.d-file
- Several isolated HHVM instances can be started
- HHVM runs as restricted user hhvm
- Added patch for FindLibMagickWand.cmake
- Added possibility to pass additional options when configuring and
building HHVM (HHVM_OPTS in make.conf)

Closes #8
Fixes #9
Closes #10