Add an all-in-one lint checking script

(imported from commit 1fbbfd2c775729295a7a061ead67812a963dc924)

tools/check-all

@@ -0,0 +1,17 @@
+#!/bin/bash
+
+SCRIPT_DIR="$(readlink -f "$(dirname "$0")")"
+EXITCODE=0
+
+if ! "$SCRIPT_DIR"/jslint/check-all; then
+    EXITCODE=1;
+fi
+
+if find "$(readlink -f "$SCRIPT_DIR"/..)" -name confirmation -prune -o -name '*.py' -print0 \
+    | xargs -0 pyflakes \
+    | grep -v 'imported but unused'; then
+
+    EXITCODE=1;
+fi
+
+exit $EXITCODE