fixes #552 - About menu drop down: Color change
fixes #552 - refactor to right css file
fixes #552 - fix a href margins so that going on to the space on data won't toggle the about menu
fixes #552 - fix old menu also
fixes #527 - /Dataset: Default sort should be last modified
Merge pull request #554 from OCHA-DAP/arti-sprint-18

Arti sprint 18