reference global logrus (#274)

* reference logrus' global logger instead of passing and storing a logger reference everywhere

* always directly use global logrus logger instead of referencing an instance

* test suites should also directly use the global logrus logger

* rename gin logging function to clarify that it's middleware

* correct comments which erroneously referenced removed logger parameter

* setting log level for tests now uses logrus' exported type instead of the string value, to guarantee error isn't possible

internal/api/s2s/user/userget.go

@@ -37,7 +37,7 @@ import (
 // And of course, the request should be refused if the account or server making the
 // request is blocked.
 func (m *Module) UsersGETHandler(c *gin.Context) {
-	l := m.log.WithFields(logrus.Fields{
+	l := logrus.WithFields(logrus.Fields{
 		"func": "UsersGETHandler",
 		"url":  c.Request.RequestURI,
 	})