Update JSessionTest.php
Use JSession to get the session ID
Mock the session
Use JUser::getInstance

This removes half of the JSession dependency in the method.
Mock the session for JFactory::getUser
No session dependency means we don't need session_id check
Merge pull request #266 from wilsonge/patch-27

Use JSession to get the session ID
Merge pull request #265 from wilsonge/patch-26

Update JSessionTest.php
Merge remote-tracking branch 'joomla/3.4-dev' into sessionTests
Merge branch 'sessionTests' of github.com:joomla-projects/joomla-cms into sessionTests
WIP