hg: jmc/jmc: JMC-6022: Use hg changeset in version properties

[klara.ward at oracle.com]

Changeset: f53acaca7a1c
Author:    klward
Date:      2018-06-04 10:32 +0200
URL:       http://hg.openjdk.java.net/jmc/jmc/rev/f53acaca7a1c

JMC-6022: Use hg changeset in version properties
Use create goal from buildnumber plugin to get hg changeset as buildNumber. Will also work for git if changing the scmConnection property.
Reviewed-by: hirt

! application/org.openjdk.jmc.rcp.application/src/main/resources/about.mappings
! application/org.openjdk.jmc.ui.common/src/main/resources/version.properties
! pom.xml