fixes #457 added xml parse operator to parse and pick values from xml nodes and att...

...ributes

Squashed commit of the following:

commit 47d8c47
Author: Ashwin Chandra Putta <ashwin@datatorrent.com>
Date:   Fri Jan 3 20:28:18 2014 -0800

    optimized logic

commit e0fad93
Author: Ashwin Chandra Putta <ashwin@datatorrent.com>
Date:   Fri Jan 3 20:27:52 2014 -0800

    added latest xerces library for xml parsing

commit acf5b5a
Merge: 54b51d6 54cc236
Author: Ashwin Chandra Putta <ashwin@datatorrent.com>
Date:   Fri Jan 3 14:56:37 2014 -0800

    Merge branch 'telecom' of https://github.com/DataTorrent/Malhar into xmlparser

commit 54b51d6
Author: Ashwin Chandra Putta <ashwin@datatorrent.com>
Date:   Fri Jan 3 14:55:30 2014 -0800

    warnings and imports

commit 26aaf01
Author: Ashwin Chandra Putta <ashwin@datatorrent.com>
Date:   Fri Jan 3 14:39:46 2014 -0800

    added test for XMLParseOperator

commit 737ff57
Author: Ashwin Chandra Putta <ashwin@datatorrent.com>
Date:   Thu Jan 2 15:39:39 2014 -0800

    added xml parse operator