[VOL-5272] - Fixed a problem with relative paths.

app-install.sh
Makefile
--------------
  o Add SPDX copyright tags.
    https://spdx.github.io/spdx-spec/v2.3/file-tags.
  o Create named test-* targets so 'make test' can be conditional.
  o No need to invoke tests/version-check for a non-release job.

app-install.sh
--------------
  o set -euo pipefail to detect shell problems.
  o Added ERR signal handler, display a stack trace for ($? != 0).
  o Added args --download and --install to begin weakening dependency
    on global variables.
  o Script now verbose when run.  Display banners, paths, artifacts, etc.
  o Replace cp with "rsync --checksum" everywhere for file copying.
  o Display contents of app.xml when unable to parse name=.
    Also display grep and sed output then fail hard.

test
test/bats/makefile
test/bats/display-help.sh
-------------------------
  o Add initial support for the bats testing harness (shell scripts).
  o Create a stub unit test directory to automate testing app-install.sh

Change-Id: I138fd2218a10121fbcce4fa8dbcf5776278d05ac
diff --git a/test/bats/urls b/test/bats/urls
new file mode 100644
index 0000000..e010974
--- /dev/null
+++ b/test/bats/urls
@@ -0,0 +1,2 @@
+https://opensource.com/article/19/2/testing-bash-bats
+https://github.com/ztombol/bats-assert