$reward xp and gold should be optional

[7uci3n]

As a DM, I want to be able to omit xp and/or gold values when using the reward command as I might not give out those rewards in a session and don't want to explicitly type them in every time if not necessary.

Now this one I did not think about when writing the spec. Some sessions might not even give rewards to players but should still be counting for the DMs efforts (like extended roleplay sessions etc.)
No reason to not make these values optional.

[a-h-i]

Fixed for v1.1
Requires documentation update on wiki