Activity generation and document creation bugfix

[yubrandon]

Scheduler added to refresh activities routinely
Fixed bug with mongoose model during activity document creation at the time of user signup

[DeMentidDev]

After examining the code, while it should be fine to merge given it doesn't have any noticeable conflicts, I was confused as to how exactly we can test these changes. I'd like to know prior to giving the green light.

[yubrandon]

Testing the scheduler may be a bit challenging other than editing the time locally when running the code, since it is scheduled to execute the task at midnight, but the code being executed functioned as expected and can most likely be isolated for testing. Regarding the Activity document creation, I checked the Activities collection manually for correct creation, but we will most likely have to utilize a separate testing database or collection for unit tests.

[DeMentidDev]

Upon testing your updates to the branch, I've run into the following errors on startup:

[DeMentidDev]

Alright, everything seems good to me. Go ahead and merge!