Added user login endpoint.

src/main/webapp/WEB-INF/web.xml

@@ -1,6 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!-- This web.xml file is not required when using Servlet 3.0 container,
      see implementation details http://jersey.java.net/nonav/documentation/latest/jax-rs.html -->
+<!-- PRODUCTION -->
 <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5">
     <context-param>
         <param-name>context.config.file</param-name>