Added pancakes and jam

I have added Pancake and Jam to food recipes. I have added it just
because i need to start coding somewhere and this looked like a nice
opportunity to learn new things. Pancakes are fully tested and works,
with no bugs found.
Thanks to Spheretech for sprites
Fix of potassium and phosphorus quantities in plants

I have halfed quantities of ptassium in potatoes and phosphorus in
pumpkins. Now there is about 1-2 units in normal plant...
Quick fix for pancakes
Merge remote-tracking branch 'upstream/master'

Conflicts:
	code/modules/reagents/reagent_containers/food/snacks/grown.dm
Merge pull request #281 from Tramziller/master

Added Pancakes + Repaired Potassium and Phosphorus quantities in plants