recalc scores with older dplyr 0.2

Installed new dplyr with:

```r
devtools::install_version('dplyr', version=0.2)
```

Unfortunately this means ggvis can no longer be imported so need to comment out the following line in ohicore/NAMESPACE to run ohi-global/calculate_scores_all.R:

```r
#import(ggvis)
```

Then to see with shiny comparison app update to dplyr 0.3 in order to run launch_cmp() .

```r
install.packages('dplyr')
ohicore::launch_cmp()
```

https://github.com/OHI-Science/issues/issues/270