Bug fixes + demo pages

- Fixed bug that only allowed one imageCloud per page.
- Now the settings are individual for each imageCloud instead of being
general.
- Added demo HTML pages.
Remove legacy code + bug fix + new demo pages

- Removed the injection of the "difference" function (it was legacy)
- Move the numImageClouds variable to a greater scope so it also works
when the plug-in is called in different ways.
- Fix bug that made all the imageClouds have the same speed
Code consistency changes + animation polishing

- Changed variable name to make it consistent with the rest of the
functions
- Updated the animation so the active frame is always in front (even
when it's shrinking)
Clean code + use of data- attributes instead of js

WARNING: FROM THIS VERSION (2.1.0) IMAGECLOUD MAY NOT WORK IN OLDER
BROWSERS AS IT WILL NEED HTML5 SUPPORT.

Changes:
- Replaced the use of JavaScript variables with data- attributes.
---- no need to inject JavaScript into the user's page.
---- no need to use evil eval.
---- from this version, imageCloud won't be supported by older browsers
- replaced arrays with more readable enums
- re-scoped variables, deleted unnecessary variables

Update in the demo for multiple imageclouds
Cleaning code

- removed unnecessary "/1" in numeric operations
- minified the code
- demo_single uses the minified code
Changing version number

The previous changes modified the code considerably, it could be
considered as a new release