Feature/deprecate translation selectors

This PR should close #139:
+ add i18n attributes to *.html
~ change lang.js to use i18n attributes to do localization
- remove runParallel as dependency
+ add browserify to package.json
~ update bundle.js
~ change quotes in *.html to be unified, add trailing slash for notranslate meta tag in head
- remove selectors.json
~ change generate_lang to use get-i18n
+ get-i18n.js that collects list of i18n names used in html files in given directory
+ add validate_html that simply checks for key duplicates on page