Added OBBrewHouseSettings class for storing setup constants
Filled in properties for OBYeast class
Started filling out stubs for OBRecipe
Created a Range class for displaying attenuation ranges
Added final gravity calculation to OBRecipe
Filled out OBHops ibu methods, and added unit tests for the same
Added xcuserdata to .gitignore
Removed xcuserdata from repo
Added vim swap files to .gitignore
Filled out gravity calculation for OBMalt, added unit test for same