Paywall and Moving Average Update

[tannakartikey]

• Rultor to perform migrate operation before deploy
• Procfile.dev for development. Use foreman start -f Procfile.dev to start Rails server. If foreman is not installed, install it using gem install foreman
• While updating the card details on My Account page, the button becomes gray and disabled with a disabled icon, on success or error it becomes normal again. This notifies a user that some activity is going on.
• Wrapped various Stripe calls with exception wrapper. (e.g. https://github.com/ajc113/currents/pull/145/files#diff-cd9de935101dff12ecc149fdd91761eeR5)
• Earlier, a faulty card could be updated (although subscription would not activate). Now the card will be rejected with the error message.
• Using scopes to fetch reports data for heatmaps to make the code more readable.
• Fetching events from Stripe again only in the production environment, to smooth the testing.
• If user's trial is extended on Stripe dashboard, the app will adjust to it and user will be notified
• If the charge is failed, then the user will be notified via email
• Upon card change, user will be notified via email
• If user's subscription was created from Stripe dashboard, the app will adjust and user will be notified via email.
• Sending new user and report notification only in the production environment
• Showing user's email id in nav bar if first name is not available.
• Showing next invoice date on My Account.
• Created config for Puma
• A few env variables do not require to be set in test environment i.e. Stripe, PartyFoul
• Implemented new moving average logic
• Various optimizations
• Refactors