Implement initial data loading sequence

[jeisses]

The following data needs to be loaded into the Vue data store when the app initializes:

See also: effectai/effect-network#117

• All acctaskidx for our user
• All campaigns
• All reservations for our user

To find out if campaigns are active we can use campaign.total_tasks > campaign.tasks_done

To find out if the current user has tasks left in the campaign (is a bit more tricky: for each campaign, load the oldest reservation and check if it's expired, and check that campaign.total_tasks > user_last_task.idx)