Begin work on Dark Sky API backend
Define protocol for weather service backends
Easily switch weather service backends in BBApplication
Define Dark Sky API endpoints and keys in application
Format latitude and longitude using %f formatter
Store lat/long values in Info.plist
Stub of basic service class for Dark Sky API
Load location data for Bucknell
Set deployment target to OS X 10.7

The Dark Sky API uses JSON. I don't really feel like using a third-party
JSON library just so I can continue supporting OS X 10.6, so set 10.7 as
the minimum OS version.
Stub out method for retrieving data from Dark Sky API
Declare block types for weather service success and failure
Specify handlers for weather service success and failure
Modify BBDataFile to use new success and failure handlers

Right now, it's not actually asynchronous, although the call makes it
appear to be that way. The Dark Sky API service _will_ be asynchronous,
and hopefully I can make the Bucknell service asynchronous, too, but
that update will come later.
Update weather menu using success and failure handlers

Due to the way BucknellBug was previously architected, there is now some
wonkiness in how the last updated entry on the menu is calculated; the
app reports failure, but the menu is still updated. I think this is
actually correct behavior and should work fine with the Dark Sky API
service, but it may be a bit weird, so I should keep an eye out for
that.
Remove -[BBApplication updateWeatherData:]

`-[BBApplication update:]` now does the same thing, so we can hook the
timer up to that.
Use new async calls in BBDarkSkyService
Use BBDarkSkyService for weather data

It doesn't work yet, but hey, the Bucknell service doesn't work, either,
so I might as well start testing with this.
Update group paths

I did not update the path for the Resources group because, frankly, it's
too much of a pain in the ass to fix relative paths for localizable
resources, and this work probably isn't that necessary anyway.
Use the AFNetworking framework for async web requests

Currently using v1.3.4 of the framework because that's the last version
that was compatible with OS X 10.7.
Properly reference system frameworks

Cocoa and SystemConfiguration were being linked directly to the ones in
/System, as was the old way of doing things in Xcode. Now they properly
reference the frameworks in the specified SDK.