Update README.md
More prominent alerts that the data is demo only

Added alerts to Intro and About modals
closes #24
About modal updates

Replace all instances of @fulcrumapp w/ @ebolamapdotinfo
Add how to join info
closes #26
Patch to make layer ctrl scroll on touch browsers

Known Leaflet bug: https://github.com/Leaflet/Leaflet/issues/2882
closes #25
Merge branch 'master' into gh-pages