add easyconfigs for Scalasca, Score-P, Cube and dependencies

add easyconfigs for Scalasca, Score-P, Cube and dependencies (OPARI2, OTF(2), PDT, PAPI, binutils) + minor style fixes

these are contributed by @berndmohr via https://github.com/fgeorgatos/easybuild.experimental/tree/master/users/unite

this depends on https://github.com/hpcugent/easybuild-easyblocks/pull/304 (and thus also on https://github.com/hpcugent/easybuild-framework/pull/754)