[#139] Remove client side depending on selectors.json:
+ add i18n attributes to *.html
~ change lang.js to use i18n attributes to do localization
- remove runParallel as dependency & for lang.js
+ add browserify to package.json
~ update bundle.js
~ change quotes in *.html to be unified, add trailing slash for notranslate meta tag in head

Fix error from rebase
Add some missing i18n by hand
Fix Spanish page for host.html page
- remove selectors.json
~ change generate_lang to use get-i18n
+ get-i18n.js that provides list of i18n names & contents in an object
+ add validate_html that simply checks for key duplicates on page