Fix error when row binding sdys
Fix error when row binding sdys

This is due to sdys$created being "POSIXct" instead of "Date".

```R
> sdys <- rbind(list(created = as.Date("2016-01-01"), count = min(sdys$count)), sdys, list(created = Sys.time(), count = max(sdys$count)))
 Error in rbindlist(l, use.names, fill, idcol) :
  Class attributes at column 1 of input list at position 2 does not match with column 1 of input list at position
  1. Coercion of objects of class 'factor' alone is handled internally by rbind/rbindlist at the moment.
```

RGLab/LabKeyModules,RGLab/LabKeyModules,RGLab/LabKeyModules,RGLab/LabKeyModules,RGLab/LabKeyModules,RGLab/LabKeyModules