Some OSX fixes

Hey,
The build available at sourceforge was crashing on my MacBook. I looked around the code and saw that, upon choosing FTL.app, the code tries to open /Resources directly, but there's a Contents folder before that. I added some code for fixing this, and also put the default location of the game under Steam at the list of default paths.

I had to edit net.blerf.ftl.ui.SavedGameHangarPanel, as it was referencing some non-existing constants. I suppose everything is ok, as the editor ran without issues on my computer.

[]s
Wilerson