Loading Events in ActivityLogPage should not lock up the UI

[nachmore]

[robsonj]

I have a fix for this. Will sort out a pull request when I get back to my computer. It basically loads the events on a Task worker, then returns them to be added to the observable collection on the UI thread.

Could probably do with a visual indicator though now to show that its doing something

[robsonj]

Submitted pull request #78

[robsonj]

I added a ActivityRing to show while the events are loading, I think there is a better way to enable/disable the activity ring though. I'm basically setting the IsActive property before and after the event load as I couldn't seem to get it to WPF bind to the BandCloudManager.IsLoadingEvents property. Would you mind taking a look before I submit a pull request please...

https://github.com/robsonj/unBand/commit/5a06c64f43ff1244d483680238b9b0746b879ec0