DROOLS-7456 update ASM and using shading in maven build

[tarilabs]

• Update version of ASM (so MVEL to be compatible with more recent bytecode)
• Avoid the "shading manually"
• Use standard maven-shade-plugin
• Suggest moving to next minor version to signify the change in the ASM (and shading strategy)

If there were any concern about final size of artifact using the shade plugin in compared to manually I believe it's irrelavant if compared to the current master default branch baseline (considering as well the ASM update), accounting for ~1.3%:

this PR:
-rw-r--r--  1 mmortari  staff  826384 May 31 14:21 target/mvel2-2.5.0-SNAPSHOT.jar

baseline (current master default branch):
-rw-r--r--  1 mmortari  staff  815481 May 31 14:22 target/mvel2-2.4.16-SNAPSHOT.jar

826384 / 815481
= 1.01337002334
→ ~1.3%

[jdimeo]

This broke the proper construction of the sources .jar