Add an install-dev option to the makefile + documentation.
Merge pull request #164 from SBSTP/install-dev

Add an install-dev option to the makefile + documentation.
- Fixed issues with install-dev
Update README.md
Update README.md
Update README.md
Merge branch 'master' of github.com:maximecb/Higgs into dev-maxime
- Implemented Object.seal, Object.freeze
- Added tests
- Removed VM args from GCRoot objects