Fixes micwallace/reddinator#34 - If a thumbnail will be too large as …

[lifeweaver]

…a bitmap, make sure to scale it down to avoid crashing. See https://developer.android.com/topic/performance/graphics/load-bitmap

[lifeweaver]

Note: WidgetService.java:365 might need similar treatment, but I didn't change it as I don't know how to test that part.