Add vendor/bin path to beginning of PATH environment variable. Closes #75.
Merge pull request #98 from ezzatron/feature/vendor-bin-path

Add vendor/bin path to beginning of PATH environment variable.
Support for hhvm-nightly. Closes #97.
Merge pull request #99 from ezzatron/feature/hhvm-nightly-support

Support for hhvm-nightly.
Remove Phake dependency, update other dependencies. Closes #80.