Refactor authentication system to use username instead of email; implement change password functionality and logging; add NLog for logging support

nlog.config

@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"
+      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+      autoReload="true"
+      throwConfigExceptions="true"
+      internalLogLevel="Warn">
+
+  <targets>
+    <target xsi:type="Console" name="console"
+            layout="${longdate}|${uppercase:${level}}|${logger}|${message} ${exception:format=tostring}" />
+    <target xsi:type="Debugger" name="debug"
+            layout="${longdate}|${uppercase:${level}}|${logger}|${message} ${exception:format=tostring}" />
+  </targets>
+
+  <rules>
+    <logger name="*" minlevel="Debug" writeTo="console,debug" />
+  </rules>
+</nlog>