Miscellaneous build improvements

 * consolidate common versions in dependencyManagement section
 * clean up OSGi metadata (remove asm/cglib imports, fix version range to account for Guava's versioning scheme)
 * update jarjar-maven-plugin to 1.9 (makes sure manifest is first entry in final jar)
 * attach correct pre-jarjar'd classes
 * fix old references to Java5
 * remove out-of-date asm:asm exclusion
 * fix versions of mini/service extensions