Add base `Mining` scaffold

Closes #20 (closed)

What

After a mining has been done on a given planet we sent out an event of the amount mined.

The following POST request is created from the client:

• Create Mining model
• Create MiningsController
• Handle the post request in the create controller function
• The function needs to check if the given resource_type exists on the planet
• Reduce the current_amount of the Resource
• If there is a lesser amount than requested we sent out the amount which they were able to mine until current_amount = 0
• Save the total amount mined