Add arm as a compile target

ci/before_install.bash

@@ -0,0 +1,29 @@
+#!/usr/bin/env bash
+
+set -ex
+
+if [ "$TRAVIS_OS_NAME" != linux ]; then
+    exit 0
+fi
+
+sudo apt-get update
+
+# needed for musl targets
+sudo apt-get install -y musl-tools
+
+# needed to build deb packages
+sudo apt-get install -y fakeroot
+
+# needed for i686 linux gnu target
+if [[ $TARGET == i686-unknown-linux-gnu ]]; then
+    sudo apt-get install -y gcc-multilib
+fi
+
+# needed for cross-compiling for arm
+if [[ $TARGET == arm-unknown-linux-gnueabihf ]]; then
+    sudo apt-get install -y \
+        gcc-4.8-arm-linux-gnueabihf \
+        binutils-arm-linux-gnueabihf \
+        libc6-armhf-cross \
+        libc6-dev-armhf-cross
+fi