make compile instructions available again

[krichter722]

Due to the fact that the link to http://bitcoinarmory.com/index.php/building-armory-from-source is no longer available, there're no instructions on how to compile from source. Maybe it's possible to add the instructions into README.md/README directly rather than making it dependent on an external resource (it's the project homepage, but it's external to github.com).

[JeffreyBytes]

Instructions for Windows can be found here: https://github.com/etotheipi/BitcoinArmory/blob/master/WindowsBuild.txt

OS X Build nots are here: https://github.com/etotheipi/BitcoinArmory/blob/master/osxbuild/osx_build_notes.txt

I cannot locate any unix build instructions.

[krichter722]

README should be updated to point there and the dead link should be removed.

[josephbisch]

There are also Ubuntu build instructions on the official Armory website.

[JeffreyBytes]

Check out my pull request https://github.com/etotheipi/BitcoinArmory/pull/257