title: R Notebooks not evaluating chunks
body: <p>I'm trying out the new R notebooks feature in Rstudio, but the chunks are not evaluating. When I preview the minimal example featured in rstudio (when you start a new file) the window says explicitly; </p>
  
  <p><code>Try executing this chunk by clicking the *Run* button within the chunk or by placing your cursor inside it and pressing *Ctrl+Shift+Enter*.</code></p>
  
  <p>However there is no "run" button in the preview and the code does not evaluate. This is what I get basically (even if I place <code>eval = TRUE</code> in the chunk options).</p>
  
  <p><a href="https://i.stack.imgur.com/7ApgI.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/7ApgI.png" alt="enter image description here"></a></p>
  
  <p>I have been all over but I can still not get the chunks to evaluate. When using a normal rmarkdown document, it evaluates with no problem. Do I have to place a specific htmlwidget or something?</p>
  
  <p>Here are my specs: </p>
  
  <pre><code>R version 3.3.2 (2016-10-31)
  Platform: x86_64-w64-mingw32/x64 (64-bit)
  Running under: Windows &gt;= 8 x64 (build 9200)
  
  locale:
  [1] LC_COLLATE=English_United States.1252  LC_CTYPE=English_United States.1252    LC_MONETARY=English_United States.1252
  [4] LC_NUMERIC=C                           LC_TIME=English_United States.1252    
  
  attached base packages:
  [1] stats     graphics  grDevices utils     datasets  methods   base     
  
  other attached packages:
   [1] tse.sql_0.1.0   memisc_0.99.7-1 MASS_7.3-45     lattice_0.20-34 foreign_0.8-67  magrittr_1.5    ggplot2_2.2.0  
   [8] inegiR_1.2.0    dplyr_0.5.0     tse.utils_0.1.0
  
  loaded via a namespace (and not attached):
   [1] Rcpp_0.12.7      knitr_1.14       munsell_0.4.3    colorspace_1.2-7 R6_2.2.0         stringr_1.1.0    plyr_1.8.4      
   [8] tools_3.3.2      grid_3.3.2       gtable_0.2.0     DBI_0.5-1        htmltools_0.3.5  lazyeval_0.2.0   yaml_2.1.13     
  [15] assertthat_0.1   digest_0.6.10    tibble_1.2       formatR_1.4      base64enc_0.1-3  evaluate_0.10    rmarkdown_1.1   
  [22] stringi_1.1.2    scales_0.4.1     XML_3.98-1.4     jsonlite_1.1     zoo_1.7-13    
  </code></pre>
  
  <p>Using Rstudio 1.0.44 and these options: </p>
  
  <p><a href="https://i.stack.imgur.com/1n4PX.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/1n4PX.png" alt="enter image description here"></a></p>
  
  <p><a href="https://i.stack.imgur.com/R9eWv.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/R9eWv.png" alt="enter image description here"></a></p>