Macosx dist package

This pr is for creating a Mac OS X distribution package. It is closer to what a typical Mac user expects when installing an app. It consists of an image file and a makefile. The makefile depends on the script create-dmg from https://github.com/andreyvit/yoursway-create-dmg.

Currently, the svg image file needs to be exported to a png using a linux version of Inkscape. The Mac version does not export it correctly. When I find a a fix for this, I'll update this. Also, this depends on the Oswald font (from the moneymanagerex.org website) being installed locally.

I put everything under build/macosx, is there a better place?