Fix title card.
Fix title card.

Prior to this CL, there was no way to hide an overridden module's title or author. Now, eliding these keys from the config will cause the title card to not show those fields.

Closes #56.

google/chicago-brick,google/chicago-brick,google/chicago-brick,lankastersky/chicago-brick,lankastersky/chicago-brick,google/chicago-brick,lankastersky/chicago-brick