Travis: added build script from master

Tools/scripts/build_all_travis.sh

+#!/bin/bash
+# useful script to test all the different build types that we support.
+# This helps when doing large merges
+# Andrew Tridgell, November 2011
+
+. config.mk
+
+set -e
+set -x
+
+echo "Testing ArduPlane build"
+pushd ArduPlane
+make configure
+for b in all apm2 sitl linux; do
+    pwd
+    make clean
+    make $b -j4
+done
+popd
+
+for d in ArduCopter APMrover2 ArduPlane AntennaTracker; do
+    pushd $d
+    make clean
+    make sitl -j4
+    make clean
+    make linux -j4
+    make clean
+    make px4-cleandep
+    make px4-v2
+    popd
+done
+
+pushd Tools/Replay
+make clean
+make linux -j4
+popd
+
+exit 0