Move over and adapt exercise of week 2

Context

OR-Mapper_JPA_ff

Summary

• Move over content from https://m1huber@git.hsr.ch/git/Unterricht/Dbs1/JPAExercise
• Adapt package names dbs1 -> dbs2 and folders
• Add corresponding build job for Template archive and PDF
• Update link on repositories main page
• Update Dbs2 Wiki page