Calculate chance to drop using a slowly increasing function

Maximum of the function is probability of 0.75. The old system would
give a guaranteed drop at a modifier of 20. With this function the
probability is then roughly .55.
Added comment about further changes that will be needed
Updated Starting Tasks

Starting tasks updated to prevent overlap with updated Beginner's Tour. Also fleshed out the description of task colors.
Revert "mounts: remove food temporarily. merging to master so we can run schema"

This reverts commit bf8c0dd9dc1042214e5a1b92b30d0c68cf92d1ba.

Conflicts:
	dist/habitrpg-shared.js
	script/algos.coffee
Merge branch 'master' of https://github.com/therufs/habitrpg-shared

Conflicts:
	dist/habitrpg-shared.js
	script/algos.coffee
Rebalance potion drop ratios
Merge pull request #51 from therufs/master

re-tweak potion ratios
Updated Starting Tasks, Mk 2

Quickedit to clarify first task.
Merge pull request #46 from BlackEdder/max_drop_chance_clean

Calculate chance to drop using a slowly increasing function
Merge pull request #49 from Xatres/master

Updated Starting Tasks
Test for food drop
Merge branch 'master' into develop