- Run android binary to update project.

- Set exit on error.
- Check if android binary exists to warn of PEBKAC.

BUILD.txt

@@ -1,10 +1,21 @@
 # To build Serval BatPhone the first time, run the following commands:
 # (or just run ./BUILD.txt, since this file is a valid shell script).
 
+# Exit on error
+set -e
+
 # Setup and clone the submodules used.
 git submodule init
 git submodule update
 
+if [ -z "`which android`" ]; then
+  echo "Unable to find android executable, have you setup your build environment correctly"
+  exit 1
+fi
+
+# Update android SDK directory in local.properties.
+android update project -t `android list targets | grep \"android-8\" | awk '{print $2}'` -p .
+
 # Build everything.
 # This calls ndk-build but you must have NDK_ROOT env var set to the root of
 # the NDK directory.