Fixed missing dependencies on package.json

[saade]

What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)

• [x] Bugfix

What is the current behavior? (You can also link to an open issue here)

Fixed missing dependencies, as described in #468

What is the new behavior?

Added:

{ 
    "buble": "^0.15.2",
    "buble-loader": "^0.4.0",
    "gulp-concat": "^2.6.1",
    "gulp-if": "^2.0.2",
    "gulp-notify": "^3.0.0",
    "gulp-uglify": "^2.0.1"
}

Does this PR introduce a breaking change?

• [ ] Yes
• [x] No

[jadjoubran]

Thanks!