Testcases development: authorization and user management

Please create a test cases for User-related scenarios: signin, signup, validation errors and so on. Test cases done should be posted as wiki pages under the test plan page. Test plan page should also reference the newly created test cases in the corresponding section.

Test plan page: http://jtalks.org/display/PM/Test+plan
Test case template: http://jtalks.org/display/PM/Test+Case+Template
User stories: http://jtalks.org/display/PM/JCommune+User+Stories+%280.2%29