Add Swedish (sv) translations

[danhe244]

I was glad to find scratchX! I want to introduce my kids to arduino and robotics and this seems like a great way to start :)

[scollovati]

@danhe244 is this translation working?

I'm trying the Italian translation but it actually does not work. For istance a simple code like this one is not working: https://user-images.githubusercontent.com/20740642/28677230-27e1da1e-72ed-11e7-98e6-bf5a7b53f57e.png

I think that this is related to the translation of strings like on/off. The same happens for a simple button pressed/released.

I already opened an Issue: https://github.com/khanning/scratch-arduino-extension/issues/62