Enhancement: Add allowed exceptions to docBlocks section of configuration

Originally created by: kbcm...@gmail.com

The sample configuration shows this:

    <!-- Tests that every function and class is immediately preceded by a docblock. A property "excludePrivateMembers" can be set if you want to disable docblocks for private member functions. -->
    <test name="docBlocks">
        <property name="excludePrivateMembers" value="true"/>
        <property name="testReturn" value="true"/>
        <property name="testParam" value="true"/>
        <property name="testThrow" value="true"/>
    </test>

I was expecting to be able to add <exception name="__toString"> to tell it that a docBlock is not required for functions with this name (since it's already pretty self-evident). If it's really that self-evident, maybe a docBlock shouldn't be required.