v1.5.9: Adding support for !groremove-ing items through their name

Changes/Fixes

• !groremove - We've added the ability to remove items by their name; no more looking at !grolist to find the item you want to delete! You can do this through !groremove Katsu, which removes "Chicken katsu" from your grocery list. This is part of our effort to make GroceryBot compatible with smart-home and general automation (p.s. GroceryBot is webhook friendly, so go ham on your automation!)
• !grolist - Added new "You have no grocery list" text when you have an empty grocery list.
• General stability and monitoring improvement, so that we can get to errors and detect anomalies quicker.