Support older Maven versions - use File[] arrays for parameters

I'm using Maven 2.2.1 in my CI environment. Using this plugin without modification gives me the following error:

```
java.lang.ClassCastException: java.lang.String cannot be cast to java.io.File
     at com.github.phasebash.jsdoc3.maven.tasks.JsDocArgumentBuilder.build(JsDocArgumentBuilder.java:65)
     at com.github.phasebash.jsdoc3.maven.tasks.JsDocTask.execute(JsDocTask.java:27)
     at com.github.phasebash.jsdoc3.maven.tasks.JsDocTasks.run(JsDocTasks.java:36)
     at com.github.phasebash.jsdoc3.maven.JsDocMojo.execute(JsDocMojo.java:95)
     ...
```

I don't understand Maven plugins enough to have any great insight into the problem, but based on a similar issue it appears that old versions of Maven don't reflect on generic collections in plugins correctly:
https://code.google.com/p/jslint4java/issues/detail?id=64
https://code.google.com/p/jslint4java/source/detail?r=0de26f13ae7fc232c886565ddb8fe909a02725e0

Based on the fix above, mine uses a File[] array for the file and directory parameters. I've tested the attached fix and it allows the plugin to run successfully on Maven 2.2.1 (as well as Maven 3.0.3, where it always worked first time).

Incidentally, I tried converting the arrays back to a generic collection inside the TaskContext.Builder(), but this lead to a MethodNotFoundException in JsDocArgumentBuilder.java:65 instead - presumably type related. I don't know enough to guess the cause of this either.

Comments welcome!