seed
Ensures that the model has some bare essentials in it.
This is called every time the application initializes. Override this if you need certain records to exist, like as how there is always one user.
As this is called every application load, if you override this, it is your responsibility to check if the model is #empty? before writing anything.
A parameter type may be given. If this is set to :sample, then
load up some sample data.