fix unit tests on node
update the grunt-browserify lib, fix the build
unit tests : be sure to rebuild before testing

When the travis job launches test-browser, the dist/ folder has not been
updated.
update the license to include zlib.js

zlib.js is included in the generated files so we should display its
license in the headers.
remove the zlib.js source map, fix #75
Merge pull request #86 from dduponchel/update_build

fix the build and the tests
move exclutions to package.json
Merge pull request #88 from calvinmetcalf/nobuffer

move exclutions to package.json
restore JSZip.defaults

JSZip.defaults has been added before the v1.0. While this object is not
documented, it may be used by people so we keep it for now.
update the generated files
JSZip 2.1.0
Merge pull request #87 from dduponchel/release_v2.1.0

Release v2.1.0