Making Maven build output less verbose

Maven emits warnings about using an environment variable as the
version. We want to keep doing this, since we have multiple Maven
projects that should all have the same version, stored centrally
in the sqenvcom.sh file.

Suppressing most Maven output, including the warning, on stdout,
but preserving the entire output in the log file
(except for the "clean" target).

Change-Id: Ifee00e65971b20b485fc2eb65fff9135250d6fe3
Merge "Making Maven build output less verbose"