Add Support for 64 bit Firefox Installations (#87)

Should fix up #87 and all the other related issues. Haven't wrote any golang for a year but I think it was a pretty simple fix so I took it on; however ff someone wouldn't mind giving it a second set of eyes that would be awesome. I'm stoked to try the app out, it's looks so cool :P

Cheers

interfacer/src/browsh/firefox.go

@@ -104,7 +104,14 @@ func ensureFirefoxBinary() {
 		}
 	}
 	if _, err := os.Stat(*firefoxBinary); os.IsNotExist(err) {
-		Shutdown(errors.New("Firefox binary not found: " + *firefoxBinary))
+		if runtime.GOOS == "windows" {
+			*firefoxBinary = `c:\Program Files\Mozilla Firefox\firefox.exe`
+			if _, err := os.Stat(*firefoxBinary); os.IsNotExist(err) {
+				Shutdown(errors.New("Firefox binary not found in: " + *firefoxBinary + " or c:\Program Files (x86)\Mozilla Firefox\firefox.exe"))
+			}
+		} else {
+			Shutdown(errors.New("Firefox binary not found: " + *firefoxBinary))
+		}
 	}
 }