Export critical environment variabiles to a .env file

[simionrobert]

The file should look like:

# Note we depend on NODE_ENV being set to dictate which of the env variables below get loaded at runtime. 
# See README for more details.

# Get this from https://mlab.com/home after you've logged in and created a database
MONGODB_URI=mongodb://<mlab_user>:<mlab_password>@<mlab_connection_url>

# This is standard running mongodb locally
MONGODB_URI_LOCAL=mongodb://localhost:27017/<database>

# Put lots of randomness in these
SESSION_SECRET=ashdfjhasdlkjfhalksdjhflak

# Facebook keys - register your app and get yours here: https://developers.facebook.com/
FACEBOOK_ID=754220301289665
FACEBOOK_SECRET=41860e58c256a3d7ad8267d3c1939a4a

# SendGrid Login - create an account with SendGrid here: https://signup.sendgrid.com/
SENDGRID_USER=myusername
SENDGRID_PASSWORD=mysecurepassword

# Application Port - express server listens on this port (default 3000).
PORT=3000