Update translatable strings

Commit 21c757a :

>modified:   src/app/language/en.json
>modified:   src/app/templates/about.tpl
>modified:   src/app/templates/settings-container.tpl
>
>- Changes strings in "about.tpl" and "settings-container.tpl" into translatable strings
>- Adds the new translatable strings in "en.json"
>- Fixes line 149 in "en.json" to fit with the actual string in "settings-container.tpl"