Fix travis configuration error.

.travis.yml

@@ -5,7 +5,7 @@ env:
   - ARDUINO_PACKAGE=arduino-1.5.2-linux64
   - ARDUINO_PACKAGE=arduino-nightly-linux64
 matrix:
-  - allow_failures:
+  allow_failures:
     - env: ARDUINO_PACKAGE=arduino-nightly-linux64
 before_install:
   - wget http://downloads.arduino.cc/$ARDUINO_PACKAGE.tgz

install.sh

@@ -1,7 +1,11 @@
-#!/bin/sh
+#!/bin/bash
 HARDWARE=~/Arduino/hardware
 TARGET=$HARDWARE/arcore
 mkdir -p $HARDWARE
-ln -s `pwd` $TARGET
-echo "Installed to $TARGET"
+if [[ -d "$TARGET" ]]; then
+  echo "Already installed at $TARGET"
+else
+  ln -s "$PWD" "$TARGET"
+  echo "Installed at $TARGET"
+fi