Speedup udf choice text only migration

Instead of blindly saving every plot and tree with a UDF, only save those
which actually require that a value be changed.
Merge branch 'master' of https://github.com/azavea/OTM2
Update to rem's for font-size, fixes compounding font-size issues
Fixes #985 - content overflowing container on static pages
Improve static page content styling and menus
Fixes #895 - Custom date fields too small to display the date
Move scientific name to second line on plot details
Fix Leaflet button position on maps
Add styling for static pages