Update tests

Outlined are the changes:

#### index.js
- remove `require Buffer`  (redundant in es5)

#### package.json
- remove gulp dependency
- remove zlib dependency (unused)
- add mocha test script

#### tests/test.js
- remove gulp tests
- reduce number of `fs` calls to increase speed

#### tests/expected
- add expected results

#### .npm/git ignore
- add npm and git ignore

#### .travis.yml
- add Travis support

#### examples/
- add example gulpfile.js

#### README.md
- add Travis badge