Add Travis tests for CORXY and COREXZ

.travis.yml

   - sed -i 's/\/\/#define FILAMENT_LCD_DISPLAY/#define FILAMENT_LCD_DISPLAY/g' Marlin/Configuration.h
   - rm -rf .build/
   - DISPLAY=:1.0 ~/bin/arduino --verify --board marlin:avr:mega  Marlin/Marlin.ino
+  # Enable COREXY
+  - cp Marlin/Configuration.h.backup Marlin/Configuration.h
+  - sed -i 's/\/\/#define COREXY/#define COREXY/g' Marlin/Configuration.h
+  - rm -rf .build/
+  - DISPLAY=:1.0 ~/bin/arduino --verify --board marlin:avr:mega  Marlin/Marlin.ino
+  # Enable COREXZ
+  - cp Marlin/Configuration.h.backup Marlin/Configuration.h
+  - sed -i 's/\/\/#define COREXZ/#define COREXZ/g' Marlin/Configuration.h
+  - rm -rf .build/
+  - DISPLAY=:1.0 ~/bin/arduino --verify --board marlin:avr:mega  Marlin/Marlin.ino
   ######## Example Configurations ##############
   # Delta Config (generic)
   - cp Marlin/example_configurations/delta/generic/Configuration* Marlin/

Marlin/Configuration.h

 // @section machine
 
 // Uncomment this option to enable CoreXY kinematics
-// #define COREXY
+//#define COREXY
 
 // Uncomment this option to enable CoreXZ kinematics
-// #define COREXZ
+//#define COREXZ
 
 // Enable this option for Toshiba steppers
 //#define CONFIG_STEPPERS_TOSHIBA