Add install script (#176)

Simplify the install process by adding a lightly configurable install script based on the README.md instructions.

install.sh

@@ -0,0 +1,38 @@
+#!/usr/bin/env sh
+
+SELECTED_USER="$1"
+CURRENT_UID="$(id -u)"
+
+if [ "$SELECTED_USER" = "" ]; then
+    echo "Please specify a user!"
+    exit 1
+fi
+
+if [ $CURRENT_UID -ne 0 ]; then
+    echo "Please run using sudo!"
+    exit 1
+fi
+
+if [ "$USE_SYMLINK" = "true" ]; then
+    ln -sf "$PWD"/51-android.rules /etc/udev/rules.d/51-android.rules
+else
+    cp -v 51-android.rules /etc/udev/rules.d/51-android.rules
+fi
+    chmod a+r /etc/udev/rules.d/51-android.rules
+if [ "$USE_GROUP" = "false" ]; then
+    mkdir -p /usr/lib/sysusers.d/ && sudo cp android-udev.conf /usr/lib/sysusers.d/
+    systemd-sysusers
+else
+    groupdel adbusers
+    groupadd adbusers
+fi
+
+usermod -a -G adbusers "$USER"
+udevadm control --reload-rules
+
+if [ "$USE_SERVICE_CMD" = "true" ]; then
+    service udev restart
+else
+    systemctl restart systemd-udevd.service
+fi
+