Connect Database to UI elements

Closes #7 (closed).

Completed the following:

• Store tasks in a mutable list of Task types
• Update Task model
  • Change id field to UUID type
  • Change dueDate field to Date type
  • Change weight field to Double
• Update the create new task modal to support new data types in the Task model
• Support fetching tasks from the database on application startup
• When a new task form is submitted, insert it into the database and update the tasks mutable list