Fix installing from git repository

issues:
* `src` is not compiled to `lib` on istalling from a git repository

fixes:
* removed `src` from `.npmignore` ~ more info http://grokbase.com/t/gg/coffeescript/124mmcmrax/module-best-practice-question-compile-pre-publish-or-pre-post-install
* restored npm postinstall (was removed in 5eab0c5) ~ more info https://github.com/paulmillr/chokidar/issues/36
* fixed coffee-script compilation on installing from a git repository when coffee-script is a parent dependency and is not linked to node_modules subdirectory ~ issue description https://github.com/isaacs/npm/issues/3217