* Add eslint to travis.yml
* Update eslint package versions and apply new indent rules
* Enable the brace-style and block-style eslint rules
* Enable the 'curly' eslint rule
* Enable the 'keyword-spacing' eslint rule
* Enable the 'key-spacing' eslint rule
* Enable the 'object-curly-spacing' eslint rule
* Enable the 'no-new-object' eslint rule
* Only disable the no-caller eslint rule in the one affected file
* Enable the 'no-unused-vars' eslint rule for local variables
* Add linting of JS in .php files