Fix Health Boost Potion

[ktksan]

The Health Boost Potion is supposed to increase the user's base max health by 50% for 30 seconds. But right now what it ends up doing is reducing health. See:

A good place to start could be trying to understand how the various Potion Authority Systems work and how the effect: "TEMP_MAX_HEALTH_BOOST" fits in there.
To try the potions: Enable the Potions module and start the game in the JS or Core Gameplay game modes and then use 'give' command in the console to obtain the potions.