Feature: Tag weights and bug fixes

[matt-d-rat]

• Updated the implementation to support tag weights.
• Updated the Readme.md with example
• Ensured backwards compatibility for usage without tag weights
• Fixed bug which caused all slide content to become wrapped in <span> tags, including the slide notes.
• Refactored the code into functions for easier readability
• Supports markdown and html slides
• Supports mixture of tags with or without tag-weights

Example usage:

<section tagcloud>
    <span tagcloud-weight="10">Twitter Bootstrap</span>
    <span tagcloud-weight="3">jQuery</span>
    less
    <span tagcloud-weight="7">GruntJS</span>
    <span>Markdown</span>
</section>

Output:

DOM output: