Feature/add jwt secret

[briri]

Fixes AWS issue #71
A step toward #153 by placing the JWTSecret in SSM

• Discovered that we worked on Update Sceptre configs to use sceptre-ssm-resolver #152 in the main account but did not update all of the new Sceptre configs in development, so switched all instances of !ssm_parameter to !ssm
• Added new ENV variable to ecs-backend
• Added new ENV variable to ecs-frontend
• Updated Wiki Installation page and ruby helper script with instructions on how to add JWTSecret to SSM
• Updated ALB template to use new Apollo Server endpoints (there is a limit of 10 paths per listener rule, so had to add an additional one)
• Removed an old unused Cognito client (added when we tested out using Cognito for UI auth)
• Updated the Cognito Outputs to export the correct credentials for the Apollo Server