Hide explore map, edits, and manage links on small screens

The /edits page and the /management pages look quite bad on small screens,
and the "Explore Map" link is taking up valuable screen real estate.
Prevent the top navbar links from disappearing on small screens
Hide logo and shrink location search on small screens.

For exceptionally small screens, remove location search altogether
Hide the stats/export bar on small screens

Exporting doesn't make much sense on a phone, and the add tree button
can be accessed from the "+" in the top-left.

Losing the tree/plot counts isn't great, but we need the real estate
Fix navbar dropdown styling for small screens.
Move sidebar below the map on smaller screens
Fix add tree process for small screens.

Lots of elements needed overflow overriden.
We don't want scrolling inside of DIVs on mobile,
we want the entire page to scroll
Hide stewardship search on small screens.

Unfortunately, there is just no way to fit this.
Prevent advanced search ranges from wrapping on small screens
Place login/signup/logout/profile into dropdown on small screens
Redo navbar changes to remove inline-flex
Switch to using $screen-xs variable for media queries
Merge pull request #1811 from maurizi/be-responsive

Use responsive design to make website useable on small screens (like phones)