wipe out master branch, point to dev/prod

- master isn't used anywhere, so to prevent accidental commits, it's 
being wiped out except for license and readme
- the readme has been updated to explain and link to the dev and prod 
branches, which is where all the code is

Author: dfarrow0

README.md

@@ -1,12 +1,38 @@
 # Status
 
-[![Deploy Status](https://delphi.midas.cs.cmu.edu/~automation/public/github_deploy_repo/badge.php?repo=cmu-delphi/www-crowdcast)](#)
+[![Deploy Status](https://delphi.midas.cs.cmu.edu/~automation/public/github_deploy_repo/badge.php?repo=cmu-delphi/www-epicast)](#)
 
 # About
 
-The Crowdcast website for collecting flu forecasts.
+The Crowdcast website for collecting flu forecasts. (Previously known as
+Epicast.)
 
-The site is live at:
-- https://delphi.cmu.edu/crowdcast
+The site is live at https://delphi.cmu.edu/crowdcast.
 
-A live demo is available at http://demo.epicast.net/ (User ID is `00000000`)
+# Branches
+
+The website is deployed to two separate environments: `dev` and `prod`. The
+code for those environments is kept in the
+[`dev`](https://github.com/cmu-delphi/www-epicast/tree/dev) and
+[`prod`](https://github.com/cmu-delphi/www-epicast/tree/prod) branches,
+respectively.
+
+## `dev` branch
+
+The `dev` branch is deployed to a Delphi-internal development environment where
+we can iterate quickly without worry of breaking the production site.
+
+## `prod` branch
+
+The `prod` branch is deployed to a public-facing production environment. It
+should contain only tested and reliable code.
+
+## process
+
+Changes are selectively merged into `prod` from `dev` after testing. However,
+**`prod` should not be updated while a forecasting round is active** (i.e.
+Friday through Monday), except in case of a critical bugfix.
+
+In any case, all code commits to `prod` should only consist of merges from
+`dev`, rather than direct commits. (An exception to this is configuration,
+which differs between environments.)