account for content wrapped in <p> tags & various fixes

[ndimatteo]

I found this plugin incredibly useful, until the content I was trying to shorten was user-generated from a wysiwyg. Most content gets wrapped in <p> tags, so it's not just 'floating.' This caused the plugin to break, as it didn't know how to properly handle them, as they were not tags within the text to be truncated, but rather wrapping the entirety of the content.

This pull request does a few things:

1. Update the copyright to 2014
2. use <div> tags for the shortcontent and allcontent wrappers (better semantically, as <p> tags within <span> tags is... weird)
3. integrates issue Can the HTML tag protection stuff be simplified? #7 that @henrythewasp addressed
4. removes bottom margin from last <p> tag in shortcontent (so it actually appears cut off)
5. wraps ellipses text in a <span> with a class of ellip so you can style

If anyone has a better approach to account for <p> tags and other wrapping elements, share em in the comments.

[ndimatteo]

I should add, that using <div> tags in place of <span> tags is not just for semantic reasons, it's also because <p> tags are inherently block items, while <span> tags are inline. Using divs allows you to show/hide any block level element without any weirdness. Sort of like a catchall.