Add envvars for deploying to cloud providers
Add joining of multiple accounts
Add account buttons to join more accounts
Migration to Express 4.x

Please see the Express documentation for details.

connect-mongo NPM package is currently broken with Express 4.x. Use
this fix in the meantime:
https://github.com/kcbanner/connect-mongo/issues/103#issuecomment-400800
50 .
Merge branch 'pr/18' into 0.2.3
Merge branch 'pr/14' into 0.2.3
Merge branch 'pr/15' into 0.2.3