Add linting for shell scripts

This changes tidy to check shell scripts for the proper shebang and
options.  It does not check that variables are formatted correctly.  It
also adds a check for the MPL 2.0 license in shell scripts.

etc/ci/check_no_unwrap.sh

@@ -1,12 +1,17 @@
 #!/usr/bin/env bash
-#
+
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
 # Make sure listed files do not contain "unwrap"
 
 set -o errexit
 set -o nounset
 set -o pipefail
 
-cd "$(git rev-parse --show-toplevel)" # cd into repo root so make sure paths works in any case
+# cd into repo root to make sure paths work in any case
+cd "$(git rev-parse --show-toplevel)"
 
 # files that should not contain "unwrap"
 FILES=("components/compositing/compositor.rs"

etc/ci/lockfile_changed.sh

@@ -1,5 +1,9 @@
 #!/usr/bin/env bash
 
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
 set -o errexit
 set -o nounset
 set -o pipefail

etc/ci/manifest_changed.sh

@@ -1,5 +1,9 @@
 #!/usr/bin/env bash
 
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
 set -o errexit
 set -o nounset
 set -o pipefail
@@ -7,8 +11,8 @@ set -o pipefail
 # We shouldn't need any binary at all to update the manifests.
 # Adding "SKIP_TESTS" to skip tests, it doesn't really skip the tests.
 # It will run "run_wpt" with "'test_list': ['SKIP_TESTS']",
-# and then pass it into wptrunner, which won't be able to find any tests named "SKIP_TESTS",
-# and thus won't run any.
+# and then pass it into wptrunner, which won't be able to find any tests named
+# "SKIP_TESTS", and thus won't run any.
 # Adding "--binary=" to skip looking for a compiled servo binary.
 ./mach test-wpt --manifest-update --binary= SKIP_TESTS > /dev/null
 

etc/ci/upload_docs.sh

@@ -1,5 +1,9 @@
 #!/usr/bin/env bash
-#
+
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
 # Helper script to upload docs to doc.servo.org.
 # Requires ghp-import (from pip)
 # GitHub API token must be passed in environment var TOKEN
@@ -16,7 +20,8 @@ cp etc/doc.servo.org/* target/doc/
 
 python components/style/properties/build.py servo html
 
-OUT_DIR="`pwd`/target/doc/servo" make -f makefile.cargo -C components/script dom_docs
+OUT_DIR="$(pwd)/target/doc/servo" \
+  make -f makefile.cargo -C components/script dom_docs
 rm -rf target/doc/servo/.cache
 
 ghp-import -n target/doc

etc/ci/upload_nightly.sh

@@ -1,5 +1,9 @@
 #!/usr/bin/env bash
 
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
 set -o errexit
 set -o nounset
 set -o pipefail
@@ -12,7 +16,7 @@ usage() {
 
 
 upload() {
-    local package_filename 
+    local package_filename
     package_filename="$(basename "${2}")"
     local -r nightly_upload_dir="s3://servo-builds/nightly/${1}"
     local -r package_upload_path="${nightly_upload_dir}/${package_filename}"