Fixed Arduino SDK download url for Linux in 'travis', was 32-bit instead of 64.

Author: MrPointer

.travis.yml

@@ -15,7 +15,7 @@ addons:
 before_install:
 - |
   if [[ $TRAVIS_OS_NAME == linux ]]; then
-    export ARDUINO_SDK_FILE="arduino-$ARDUINO_SDK_VERSION-linux32.tar.xz"
+    export ARDUINO_SDK_FILE="arduino-$ARDUINO_SDK_VERSION-linux64.tar.xz"
   else
     export ARDUINO_SDK_FILE="arduino-$ARDUINO_SDK_VERSION-macosx.zip"
     brew update