Bugfixes for view server

- the default case for docs without emit did not work:
(lambda (doc) (if nil (emit 1 1)))
It works properly after removing the outer list

- parameter value in emit should be optional to reflect usage in futon/javascript
I think (lambda (doc) (emit 1)) should behave like function(doc) emit(1), i.e. give (emit 1 nil)

- README file had wrong call for query-view-server

- prin1-to-string does pretty printing, but the code cannot handle pretty printed strings -> I would suggest to change README line to write-to-string