Auto comment - WIP

[jsatterfield]

Enable auto commenting by passing query_trace=True and optionally trace_depth=N (defaults to 3) to mongoengine.connect()
Enable the mongo system profiler by connecting to your local mongo and set db.setProfilingLevel(2) on your database.

$ mongo
MongoDB shell version v3.6.5
connecting to: mongodb://127.0.0.1:27017
> use test
switched to db test
> db.setProfilingLevel(2)
{ "was" : 0, "slowms" : 100, "ok" : 1 }
>

This covers most read ops. Inserts, updates, upserts, findAndModify, etc wont get comments.
Example system.profile doc with comments:

$ mongo
MongoDB shell version v3.6.5
connecting to: mongodb://127.0.0.1:27017
> use test
switched to db test
> db.system.profile.find({"ns": { $ne: "test.system.profile"}}).sort({$natural: -1}).limit(1).pretty()
{
	"op" : "query",
	"ns" : "test.foo",
	"query" : {
		"find" : "foo",
		"filter" : {
			"first_name" : "James"
		},
		"ntoreturn" : -1,
		"comment" : [
			"<ipython-input-4-460f39f6836a>(1)",
			"/Users/jsatterfield/venv/test/lib/python2.7/site-packages/IPython/core/interactiveshell.py(2869)",
			"/Users/jsatterfield/venv/test/lib/python2.7/site-packages/IPython/core/interactiveshell.py(2815)"
		]
	},