fixes multiple issues parsing attributes

Before https://github.com/Schlaefer/jBBCode/commit/cd809f9cb86560dc3d4436b33ccab5e40192516e the attribute-value was split on the `=` resulting in an attribute value `http://jbbcode.com/?b`. There was no test case indicating that something was wrong, now with that same bug it would show:

    1) SimpleEvaluationTest::testCodeOptions
    Failed asserting that two strings are equal.
    --- Expected
    +++ Actual
    @@ @@
    -'This contains a <a href="http://jbbcode.com/?b=2">url</a> which uses an option.'
    +'This contains a <a href="http://jbbcode.com/?b">url</a> which uses an option.'