updated meta() with sendToHeader argument

Added sendToHeader argument to allow for meta tags to be written into the buffer / header of the html document
updates to link()

- extended link() method to support canonical links
http://support.google.com/webmasters/bin/answer.py?hl=en&answer=139394
- added support to send directly to header
Merge pull request #125 from guardly/feature/HTMLHelper-updates

Feature/html helper updates