Issue #2488116 by dipen chaudhary, cpj, ashutoshsngh, joachim, znerol, priya.chat, jhodgdon, anavarre, jmarkel: Document the session subsystem

Issue #2619332 by joelpittet, jmarkel, Wim Leers, Berdir, chintan.vyas, netsensei: Color scheme config changes aren't reflected in cached pages

Issue #1906692 by Simon Georges, jmarkel: String cleanup: make strings consistent in DefaultFetcher::fetch.

Issue #1886498 by jmarkel: Fixed With Bartik, and browser window is wide, module page layout unusable.

Issue #1500160 by jmarkel, tstoeckler: Better documentation for hook_block_info, especially the pages component