add parametrization for endpoint tests

adds a tiny bit of tests to raise the coverage

    ᓆ py.test
    ========================================= test session starts ==================
    platform darwin -- Python 2.7.6 -- py-1.4.26 -- pytest-2.6.4
    plugins: cov
    collected 53 items
    
    tests/test_client.py .....................................................
    
    =================================== 53 passed in 0.24 seconds ==================

    -------------------- coverage: platform darwin, python 2.7.6-final-0 -----------
    Name                Stmts   Miss  Cover
    ---------------------------------------
    __init__                0      0   100%
    cli                   167    167     0%
    client                255     82    68%
    lock                   68     68     0%
    sync                  201    201     0%
    tests/__init__          0      0   100%
    tests/test_client     121      0   100%
    worker                334    334     0%
    ---------------------------------------
    TOTAL                1146    852    26%