Allow calling faker methods with arguments

[mpociot]

This PR adds the ability to call more complex faker methods.

It follows an easy convention: FAKER_methodName:arguments The arguments of the faker method can be separated by a comma.

Examples:

<?xml version="1.0" ?>
<slimdump>
    <table name="users" dump="full">
        <column name="username" dump="replace" replacement="FAKER_word" />
        <column name="password" dump="replace" replacement="test" />
        <column name="amount" dump="replace" replacement="FAKER_numberBetween:1,100" />
        <column name="lastname" dump="replace" replacement="FAKER_numerify:'Helo ###'" />
        <column name="email" dump="replace" replacement="FAKER_unique->randomDigitNot:0" />
    </table>
</slimdump>

Edit: I haven't changed the README yet, as I wasn't sure if you want this PR. If this gets merged, I can prepare a PR that modifies the documentation.

[janopae]

This is indeed a nice addition to the featureset of slimdump!

Are there any reasons to not use parantheses here (like FAKER_unique->randomDigitNot(0))? I think the closer we stay to the PHP syntax the better, as this removed the mental load of translating the Faker documentation into our own syntax.