Add common-functions.sh bash lib

Add common-functions.sh bash lib

tired of looking at duplicated code and having to remember to
search for all instances of it. This can be the start of some
cleanup, if others agree it's a good idea.

first round:
  - move the Java vars setup code to a common function.
  - move some common vars to common location as well
  - added "export" to some vars to get around local tox
    shellcheck error

Change-Id: If03949e16aae3561ac8636bc4de0b1a17dad01ae
Signed-off-by: Jamo Luhrsen <jluhrsen@redhat.com>