added user menu with logout

modified nav bar to include user menu, needs to be modified for small
screen sizes
changed index, added analytics page and fixed login

rearranged the overview page, put all the graphs in a new analytics page
with the excel export button. Changed css for the user menu in the nav
bar which disappears on small devices and is replaced by a small
dropdown in the sidebar
Merge remote-tracking branch 'origin/back-end-dev'