First class ARM support

[marekmaskarinec]

I've tested that tophat can run on linux arm devices like the raspberry pi, however no binaries for these platforms are offered.

[vtereshkov]

At least it requires a permanent access to an ARM platform. Even when you have it, a new build always means a lot of testing, which is only justified by having real users.

I gave up the idea of releasing Umka for Aarch64, even though I had a very positive experience with it.