User accounts and log in

[lxtlouise]

1. For Colfusion users, before they visualize the datasets, they should log in to the system. But they don't need to create new accounts;
2. For other new users, before they visualize the datasets, they should create new accounts and log in to the system.

[lxtlouise]

Please check VisualizationTest I submitted. You can check how to write junit test for each function. Besides, please check the website: http://junit.org This website tells you how to write junit test. Thank you.