Added regexp to remove all scripts elements
Don't match JavaScript comments and strings when removing script tags.
First remove HTML comments and CDATA sections.
Next remove the script tags.

Fixes oscarotero/Embed#13
Merge pull request #14 from jasny/remove_scripts

Don't match JavaScript comments and strings when removing script tags.
Merge pull request #15 from oscarotero/remove_scripts

Remove scripts, comments and cdata sections to avoid problems in the DOMDocument