Add adaptive scoring mode

[sig1nt]

Every question starts at the same point value, and then drops be a certain increment based on the number of people who have solved a challenge. Should be a toggle in the config.

[slashnick]

So each challenge is worth max(base - incr * solves, minimum)?

The team ranking query is going to be so cool.

[sig1nt]

Considering how points as of now are just derivative of a SQL query, we should be able to just supplant that based on some flag in the config file

[slashnick]

We're currently using SQLAlchemy to map Python object properties to database columns. For example, the property Challenge.points directly maps to the column points in the table challenge.

I wonder if there's a way to define a property (eg. Challenge.points) as something SQL should compute based on other columns, like the formula above. It would be really nice if, any time we select a Challenge, SQLAlchemy automatically adds some + math * here AS points into the query. It may even let us just do Challenge.query(...).order_by(Challenge.points), and know to order by the points pseudo-column.

[sig1nt]

Looks like we can use the @hybrid_property function decorator for exactly this.
http://docs.sqlalchemy.org/en/latest/orm/extensions/hybrid.html

[xzinkus]

We want this as toggle-able, but I think discussing whether it should be used is a conversation per-ctf.

+1'd with lowest priority