Load Prism component map at runtime

Fix #74
Better sematics in MPGetObjectFromJavaScript
Fix memory leaks in MPGetObjectFromJavaScript
Removed xib settings that seem to crash InterfaceBuilder in 10.8

Some references online that seem to indicate setting `appearanceType=“aqua”` will crash `ibtools`:
- <http://stackoverflow.com/questions/20531240/xcode-5-ibtool-failed-with-exit-code-255>
- <http://www.tyreeapps.com/blog/tools/2014/06/10/Xcode-Crash-with-xib-Files.html>