Added a SoundLoader class for simplifying the loading of sounds.
Added a TextureRegionLoader class for greatly simplifying the loading
of TextureRegions.
The TextureRegionLoader and SoundLoader classes are now properly
initialized in MainActivity.
Merge branch 'master' of github.com:LinneaAndersson/SecondHand

# Please enter a commit message to explain why this merge is necessary,
# especially if it merges an updated upstream into a topic branch.
# 
# Lines starting with '#' will be ignored, and an empty message aborts
# the commit.