Add a log in the mock environment

Add a function that implements `log()` in the mock environment.

spec/env_mock.lua

@@ -105,7 +105,7 @@ local smr_mock_env = {
 		return req.cookies[cookie_name]
 	end),
 	http_response_cookie = spy.new(function(req,name,value) req.cookies = {[name] = value} end),
-	log = spy.new(function(priority, message) end),
+	log = spy.new(function(priority, message) --[[print(string.format("[LOG %q]: %s",priority,message))]] end),
 	sha3 = spy.new(function(message) return "digest" end),
 }
 
@@ -161,6 +161,7 @@ function mock.mockdb()
 	local config = require("config")
 	config.db = "data/unittest.db"
 	assert(os.execute("rm " .. config.db))
+	package.loaded.db = nil
 	local db = require("db")
 end