Bug 998299 - Add Neo layout

[Neo](http://www.neo-layout.org/) is another layout for keyboards.

Since Neo request at least 11 keys in each line this is a adaptation
of it to mobile devices (a adaptation to Android is available at
https://play.google.com/store/apps/details?id=com.anysoftkeyboard.languagepack.neo2&hl=en).
Merge pull request #18452 from r-gaia-cs/neo-layout

Bug 998299 - Add Neo layout
r=rudylu