Allow .get to return subpackages.

Here's an example of it working:

```python
Python 2.7.3 (default, Aug  9 2012, 17:23:57) 
[GCC 4.7.1 20120720 (Red Hat 4.7.1-5)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import pkgwat.api
>>> pkgwat.api.get('ConsoleKit')
{u'upstream_url': u'http://www.freedesktop.org/wiki/Software/ConsoleKit', u'description': u'ConsoleKit is a system daemon for tracking what users are logged\ninto the system and how they interact with the computer (e.g.\nwhich keyboard and mouse they use).\n\nIt provides asynchronous notification via the system message bus.', u'summary': u'System daemon for tracking users, sessions and seats', u'link': u'ConsoleKit', u'devel_owner': u'vicodan', u'icon': u'package_128x128', u'sub_pkgs': [{u'icon': u'package_128x128', u'link': u'ConsoleKit-devel', u'description': u'This package contains headers and libraries needed for\ndeveloping software that is interacting with ConsoleKit .', u'name': u'ConsoleKit -devel', u'summary': u'Development files for ConsoleKit'}, {u'icon': u'package_128x128', u'link': u'ConsoleKit-docs', u'description': u'This package contains developer documentation for ConsoleKit .', u'name': u'ConsoleKit -docs', u'summary': u'Developer documentation for ConsoleKit'}, {u'icon': u'package_128x128', u'link': u'ConsoleKit-libs', u'description': u'This package contains libraries and a PAM module for interacting\nwith ConsoleKit .', u'name': u'ConsoleKit -libs', u'summary': u'ConsoleKit libraries'}, {u'icon': u'package_128x128', u'link': u'ConsoleKit-x11', u'description': u'ConsoleKit contains some tools that require Xlib to be installed,\nthose are in this separate package so server systems need not install\nX. Applications (such as xorg-x11-xinit) and login managers (such as\ngdm) that need to register their X sessions with ConsoleKit needs to\nhave a Requires: for this package.', u'name': u'ConsoleKit -x11', u'summary': u'X11-requiring add-ons for ConsoleKit'}], u'name': u'ConsoleKit'}
>>> pkgwat.api.get('ConsoleKit-libs')
{u'icon': u'package_128x128', u'link': u'ConsoleKit-libs', u'description': u'This package contains libraries and a PAM module for interacting\nwith ConsoleKit.', u'name': u'ConsoleKit-libs', u'summary': u'ConsoleKit libraries'}
```