Significant fix - moved one line of code

[Louis DeJardin]

Somone spotted a problem with the order viewdata and viewcontext were
assigned in the base SparkView...

http://github.com/loudej/spark/commit/55eea63579579958a699b746e0870a2ae1fcceab

This fixes an odd problem where just the strongly typed Model on the
strongly typed HtmlHelper ended up being null. If you've been having
problems with some mvc2 template helpers or mvccontrib fluent html
helpers you might want to see if that has made a difference...