Additional features for CSW QGIS plugin

 - Added ability to get bbox extension from any loaded layer in qgis.
 - Added ability to get bbox using geolocation services.
 - UI tweaks to accommodate the new features. (UI was updated with Designer)
For example, what happens if one searches for 'Waterloo', there are many examples from many countries.  Maybe presenting a list is best, limited to top 10 results?

We should ensure global search to keep things simple for now.