OPENJPA-2283 use xbean-asm4-shaded ASM version as the dynamic handling doesn't work out

This makes sure we always have a guaranteed ASM version 4 regardless what ASM a
user might add to the project. This also rolls back the dynamic ASM handling of
OPENJPA-2171.


git-svn-id: https://svn.apache.org/repos/asf/openjpa/branches/2.3.x@1530808 13f79535-47bb-0310-9956-ffa450edef68