Added PathToFileSetTask

Convert given path to a fileset.

Example:
```
 <path id="modified.sources.path" dir="C:\Path\to\phing\classes\phing\" />
 <pathtofileset name="modified.sources.fileset"
                pathrefid="modified.sources.path"
                dir="." />
 
  <copy todir="C:\Path\to\phing\docs\api">
      <mapper type="glob" from="*.php" to="*.php.bak" />
      <fileset refid="modified.sources.fileset" />
  </copy>
```