* Collect all env vars in one, easy-to-find place
Past state:
* Default environement variables were stored in both client/package.json
and client/__tests__/e2e/config.js
* Constants that should have been linked--like the cellxgene server port
during testing--were repeated.
With this commit:
* All environment variables are parameterized
* All environment variables are packaged in default env files
* Move npm scripts to client Makefile
* Respond to feedback from @seve and @bkmartinjr
* toast test
* modify webpack build to allow for global CSS; use CSS modules to scope component styling
* remove heatmap
* add label to index resets
* swapping out buttons for blueprint
* adding constants to globals
* swapping out blueprint buttons
* title position, sidebar improvements
* sidebar styles
* adding toasts for validation errors
* zebra section trial
* integrating blueprint, switching buttons over, breaking out scatter
* clean up console
