Issue #1719648 by joachim, ttkaminski, kshama_deshmukh: ModuleInstaller::install() silently fails if a module isn't in the file system

Issue #1974408 by kim.pepper, disasm, ParisLiakos, kshama_deshmukh, alexpott, theMusician, pwieck | mtift: Convert aggregator_page_source() to a Controller.