Add instructions for UI development on the Mac
Add instructions for UI development on the Mac

Primary addition is for instructions on the Mac. Also made some minor
stylistic / grammatical changes.

oleksandr-minakov/northshore,oleksandr-minakov/northshore,psumkin/northshore,carmine/northshore,oleksandr-minakov/northshore,psumkin/northshore,carmine/northshore,carmine/northshore,psumkin/northshore,carmine/northshore,oleksandr-minakov/northshore,psumkin/northshore,oleksandr-minakov/northshore,psumkin/northshore