dependency + devDependency update

Dependencies updated:

1. async: ~0.9.0 --> ~1.2.1
2. lodash.isplainobject: ~3.0.0 --> ~3.1.0
3. through2: ~0.6.3 --> ~2.0.0

DevDependencies updated:

1. express: ~4.12.2 --> ~4.13.0
2. gulp-jshint: ~1.9.2 --> ~1.11.0
3. gulp-mocha: ~2.0.0 --> ~2.1.2
4. gulp: ~3.8.8 --> ~3.9.0
5. istanbul: ~0.3.7 --> ~0.3.15
6. jshint-stylish: ~1.0.1 --> ~2.0.1
7. supertest: ~0.15.0 --> ~1.0.1