Fixing CSS selectors and broken 'Categories' test.

Adding new categories - "search tools", updating css selectors, fixing a test.

additional info:

root analysis:
self = <class unittestzero.Assert at 0x1b47c80>, first = 'Shopping', second = u'Search Tools', msg = None

    @classmethod
    def equal(self, first, second, msg=None):
        """
            Asserts that 2 elements are the same
    
            :Args:
             - First object to be tested
             - Second object to be tested
             - Message that will be printed if it fails
            """
>       assert first == second, msg
E       AssertionError: None

../../venvs/addons/local/lib/python2.7/site-packages/unittestzero.py:53: AssertionError
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> entering PDB >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> /home/jakub/venvs/addons/local/lib/python2.7/site-packages/unittestzero.py(53)equal()
-> assert first == second, msg
(Pdb) args
self = unittestzero.Assert
first = Shopping
second = Search Tools
msg = None



after fix:
1) run 
platform linux2 -- Python 2.7.4 -- pytest-2.3.5 -- /home/jakub/venvs/addons/bin/python
plugins: mozwebqa, xdist
collected 22 items 

tests/desktop/test_homepage.py:313: TestHome.test_that_checks_all_categories_side_navigation PASSED


2) run

platform linux2 -- Python 2.7.4 -- pytest-2.3.5
plugins: mozwebqa, xdist
collected 22 items 

tests/desktop/test_homepage.py .....................

 1 tests deselected by "-m 'nondestructive'" 
 21 passed, 1 deselected in 333.78 seconds ==========