Added cacheUpdated attribute to data models.
Added fileURL attribute to Spark.
Added preliminary Spark image display.
Caching of downloading images, downloading images on other thread.
Inspiration, problem, what if colors.
Fixed reuse bug with SNSparkCell.
Basic SNNewSparkViewController UI.
Merge pull request #84 from maxluzuriaga/ios-multimedia

Multimedia on iOS app
Merge remote-tracking branch 'upstream/master'