Rename and tweak

Tweak example file,
Remove comment block form ImageLoader,
Remove ImageLoader getPercentLoaded,
Rename Queue's get function to getItemAt
Simplify usage

Fix #12
Remove classes from global namespace

Remove Queue, QueueImage and Thread from global namespace by using
gulp-wrap.
Finetune gulpfile and create test tasks for minified and unminified
code.
Merge pull request #13 from jakoivis/Renaming-and-tweaking

Renaming and tweaking