now can do register and login actions
	modified:   pom.xml
	modified:   src/main/java/com/netease/blackqa/utils/CommonString.java
	modified:   src/main/java/com/netease/blackqa/utils/Main.java
	modified:   src/main/webapp/WEB-INF/web.xml
git add	src/main/java/com/netease/blackqa/servlets/LoginServlet.java
git add	src/main/java/com/netease/blackqa/servlets/RegisterServlet.java