Add Actions Model with GET capabilities

[ShaydeNofziger]

Closes #41

This pull request adds the Action model and seeds 3 Actions to the development database. Due to our limited time and prioritization of gameplay work, this PR only includes controller methods for retrieving all Actions, or retrieving a specific Action given its ID.

Example requests:

• GET /api/action
  • returns a collection of actions
• GET /api/action/:id
  • returns an action whose id === :id

Sample GET /api/action/1 Response Body:

{
  "id": 1,
  "name": "Deploy SSL/TLS",
  "description": "Deploy the widely-adopted cryptographic protocol to prevent unauthorized packet sniffing.",
  "devcaps_cost": 1,
  "mindset_reward": 0,
  "repeatable": false,
  "requires_mature": false
}