Modify splash.gradle so the build doesn't fail if the workspace is not a Git Repo.

[blu28]

If the workspace is not a git repo then the gi command called in splash.gradle will fail with an error, which in turn causes the build to fail. It would be better if the build doesn't fail, but instead an warning message is printed and the build continues, with some kind of alternate text in the deploy directory files to indicate what happened.

[blu28]

See https://stackoverflow.com/questions/34234820/gradle-exec-task-returns-non-zero-exit-value-and-fails-the-build-but-i-want-to-n
and
https://docs.gradle.org/current/dsl/org.gradle.api.tasks.Exec.html
for hints on how to do this.