Refactoring based on feedback in https://github.com/scala-ide/scala-ide/pull/482
No need to declare the Manifest version because version 2 is the default
No reason for putting the manifest in the ${basedir}
No need to put the sbt version number in the bundle name
Adding organisation information in the POM to reduce duplication
Added source bundle for Sbt compiler interface
Deleted unneeded package export from MANIFEST in compiler.interface bundle
Deleted unneeded import-package clauses in toolchain MANIFESTs

The maven build does no longer spits out warnings for unused package imports in MANIFESTs.