Spanish support

[SaulNunez]

I don't know if you accept translations yet. But I'll just leave this here

[antaxiom]

Not sure the progress on this, but I could contribute translations if needed.

[matejdro]

These native Android strings would also need to get translated:

https://github.com/pebble-dev/mobile-app/blob/master/android/app/src/main/res/values/strings.xml

[matejdro]

It is a bit early though, many of the flows (and its corresponding strings) are not ready yet, so I don't think it would be a good idea to merge this just yet.