Bug 453379 - Make sure to precompile jsps with the same Jetty version

Use jetty-version property from eclipse-platform-parent pom so jsp files
are precompiled with the same Jetty version shipped to minimize possible
incompatibilities. A change is groupId is needed for version 9.x of
jetty-jspc-maven-plugin.

Change-Id: Icbc593dcd9600ffe157f977f0cd8c74aebedfc36
Signed-off-by: Alexander Kurtakov <akurtako@redhat.com>