Add an easier HTTP GET interface for Emerson.

This version lets you just pass in a simple URL and deals with
formatting the request and handling complicated URLs with hostnames,
ports, etc. It also leaves open more flexibility for more completeness
in the requests and space for other request types as different
functions under system.http.
Fix bug in cleaning up removed chlidren in TwitterAggregateManager.

Fix issue where sometimes a parent aggregate's dirty_children entries
were not being cleaned out properly when the child was removed. This
would occur if the aggregate was being processed just at the time the
removal happened because we only did the operation if the dirty flag
was set on the child. However, since it could be marked clean but
still be processing, we need to check that flag as well.
Add simple clustering to Twitter aggregation.

Add k-means clustering of tweets to determine topics for each
aggregate, which are added to the aggregate JSON "mesh".
Add circles to clutter renderer.
Add mouse events to ClutterRenderer.
Handle aggregate removed during aggregation in TwitterAggregateManager.

TwitterAggregateManager was assuming that an object marked dirty must
still be in the tree. However, it could be removed while it's being
processed, leaving it with no parents and not in the ready
queue. Simply check if it has any parents and if not, just drop it.
Add mouse press/release support to ClutterRenderer.
Pass root aggregate query data updates to PintoServerQuerier.

When the root aggregate's query data is updated, make sure it is
passed to PintoServerQuerier. This requires a new method in the
interface and support from the proximity implementations. This also
updates the PintoServerQuerier implementations to pass this
information along to the Pinto server. The local implementation just
stores it and includes it in updates, allowing the top level Pinto to
work naturally. The real Pinto doesn't yet handle extra query data,
but the PintoServerQuerier will pass it along so it can in the future.
Add count() method to get number of positive entries in TermBloomFilter.
Remove now unnecessary bloom_empty parameters from TermBloomFilter.

They were only required because the top level of Pinto was not
handling query data properly.