🐧 Add "mktar" gulp task to create an Linux binary archive

This archive in tar.gz format contains the whole Atom binary and resources
to enable multiple channels and versions to be installed on the same
distribution.

script/mktar

@@ -0,0 +1,39 @@
+#!/bin/bash
+# mktar name version arch icon-path build-root-path
+
+set -e
+
+SCRIPT=`readlink -f "$0"`
+ROOT=`readlink -f $(dirname $SCRIPT)/..`
+cd $ROOT
+
+NAME="$1"
+VERSION="$2"
+ARCH="$3"
+ICON_FILE="$4"
+BUILD_ROOT_PATH="$5"
+FILE_MODE=755
+
+TAR_PATH=$BUILD_ROOT_PATH
+ATOM_PATH="$BUILD_ROOT_PATH/Atom"
+
+TARGET_ROOT="`mktemp -d`"
+chmod $FILE_MODE "$TARGET_ROOT"
+NAME_IN_TAR="$NAME-$VERSION-$ARCH"
+TARGET="$TARGET_ROOT/$NAME_IN_TAR"
+
+# Copy executable and resources
+cp -a "$ATOM_PATH" "$TARGET"
+
+# Copy icon file
+cp "$ICON_FILE" "$TARGET/$NAME.png"
+
+# Remove executable bit from .node files
+find "$TARGET" -type f -name "*.node" -exec chmod a-x {} \;
+
+# Create the archive
+pushd "$TARGET_ROOT"
+tar caf "$TAR_PATH/$NAME_IN_TAR.tar.gz" "$NAME_IN_TAR"
+popd
+
+rm -rf "$TARGET_ROOT"