Fix swapped default and key in QConfig.

Dependencies

• [2] M3KUPGZK Add invitation email template.
• [3] 2XQD6KKK Add invitation logic and clean up DBProg error handling.
• [4] V2VDN77H Enable postgres configuration via environment variable for Heroku.

Change contents

• replacement in server/Aftok/QConfig.hs at line 41
  [3.7925]→[2.359:438](∅→∅)
  − <*> C.lookupDefault "templatePath" cfg "/opt/aftok/server/templates"
  [3.7925]

  [3.7968]
  + <*> C.lookupDefault "/opt/aftok/server/templates/" cfg "templatePath"
• replacement in server/templates/invitation_email.st at line 3
  [2.754]→[2.754:1157](∅→∅)
  − A friend of yours ($from_email$") has invited you to join the "$project_name$" project at http://aftok.com. Here's what you need to do to accept their invitation. At present, there's no user interface for the service other than bare HTTP requests with a JSON payload. A script has been provided below that you can edit to include your own information. You'll need to replace the following three tokens:
  [2.754]

  [2.1157]
  + A friend of yours ($from_email$) has invited you to join the "$project_name$" project at http://aftok.com. Here's what you need to do to accept their invitation. At present, there's no user interface for the service other than bare HTTP requests with a JSON payload. A script has been provided below that you can edit to include your own information. You'll need to replace the following three tokens: