Add link to Winston Chang's slides

See [his tweet](https://twitter.com/winston_chang/status/484039769265938432)
Small change to text for the Winston Chang link
Add link to Ramnath's slides on rCharts
Update index.html

Added link to my slides.
Merge pull request #4 from rasmusab/patch-1

Update index.html
Added link to slides
added slides (in brackets)
Link to slides from Dirk Eddelbuettel

See tweet: https://twitter.com/eddelbuettel/status/484434107183534080
Link to slides from Tal Galili

See tweet: https://twitter.com/talgalili/status/484917338915893248
Link to slides from Jan de Leeuw

see tweet: https://twitter.com/jstatsoft/status/485183206879002625
Link to slides from David Smith

See tweet: https://twitter.com/revodavid/status/484483874336940032
Link to Jeff Allen's slides

See tweet: https://twitter.com/TrestleJeff/status/484567361790287872
Link to slides from Garrett Grolemund

see tweet: https://twitter.com/StatGarrett/status/484770964517814272
link to slides from Lou Bajuk-Yorgan

see tweet: https://twitter.com/LouBajuk/status/484727487629250560
Slides from Talita Perciano

see tweet: https://twitter.com/talitaperciano/status/484726707006349314
Slides from Rasmus Baath

see tweet: https://twitter.com/rabaath/status/484080407046926336
Slides from David Diez

see tweet: https://twitter.com/timothy_phan/status/484458750141423619
Link to poster from Mine Cetinkaya-Rundel and Andrew Bray

See tweet: https://twitter.com/minebocek/status/484595498548858880
Merge master from user2014/user2014.github.io

 - I should have pulled first before starting to add changes!
Merge pull request #7 from kbroman/more_links

Add a bunch more links to slides (and one poster)