update dotfiles

* add .jshintrc
* quicken CI build (ref: http://goo.gl/m6glri)
* remove .npmignore
use `files` field to decrease size consistently

https://docs.npmjs.com/files/package.json#files
update versions of dependencies explicitly

Probably it fixes this issue:
https://github.com/gulpjs/gulp-util/issues/69
update test script and coverage reporter script

* introduce shinnn/istanbul-coveralls
* let JSHint work correctly
* remove mocha’s —reporter option
  * Mocha uses spec reporter by default.
add trailing newlines to EOF
code refactoring for test script

* remove unused variables
* use .containEql method instead of .indexOf
* remove unnecessary trailing slashes
update badge URLs
replace lodash with smaller modules

* _.filter -> array-differ
* _.uniq -> array-uniq
* _.defaults -> object-assign