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/client/admin/domainblockcreate.go

@@ -90,7 +90,7 @@ import (
 //   '400':
 //      description: bad request
 func (m *Module) DomainBlocksPOSTHandler(c *gin.Context) {
-	l := m.log.WithFields(logrus.Fields{
+	l := logrus.WithFields(logrus.Fields{
 		"func":        "DomainBlocksPOSTHandler",
 		"request_uri": c.Request.RequestURI,
 		"user_agent":  c.Request.UserAgent(),