Error(s) in re-building vignettes:
--- re-building ‘tiler.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
Loading required package: sp
Traceback (most recent call last):
  File "/Volumes/SSD-Data/Builds/R-dev-web/QA/Simon/packages/el-capitan-x86_64/results/3.6/tiler.Rcheck/tiler/python/gdal2tilesIMG.py", line 47, in <module>
    import gdal
ImportError: No module named gdal
Traceback (most recent call last):
  File "/Volumes/SSD-Data/Builds/R-dev-web/QA/Simon/packages/el-capitan-x86_64/results/3.6/tiler.Rcheck/tiler/python/gdal2tiles.py", line 52, in <module>
    from osgeo import gdal
ImportError: No module named osgeo
Traceback (most recent call last):
  File "/Volumes/SSD-Data/Builds/R-dev-web/QA/Simon/packages/el-capitan-x86_64/results/3.6/tiler.Rcheck/tiler/python/gdal2tilesIMG.py", line 47, in <module>
    import gdal
ImportError: No module named gdal
Traceback (most recent call last):
  File "/Volumes/SSD-Data/Builds/R-dev-web/QA/Simon/packages/el-capitan-x86_64/results/3.6/tiler.Rcheck/tiler/python/gdal2tiles.py", line 52, in <module>
    from osgeo import gdal
ImportError: No module named osgeo
Traceback (most recent call last):
  File "/Volumes/SSD-Data/Builds/R-dev-web/QA/Simon/packages/el-capitan-x86_64/results/3.6/tiler.Rcheck/tiler/python/gdal2tilesIMG.py", line 47, in <module>
    import gdal
ImportError: No module named gdal
Traceback (most recent call last):
  File "/Volumes/SSD-Data/Builds/R-dev-web/QA/Simon/packages/el-capitan-x86_64/results/3.6/tiler.Rcheck/tiler/python/gdal2tiles.py", line 52, in <module>
    from osgeo import gdal
ImportError: No module named osgeo
Traceback (most recent call last):
  File "/Volumes/SSD-Data/Builds/R-dev-web/QA/Simon/packages/el-capitan-x86_64/results/3.6/tiler.Rcheck/tiler/python/gdal2tilesIMG.py", line 47, in <module>
    import gdal
ImportError: No module named gdal
PhantomJS not found. You can install it with webshot::install_phantomjs(). If it is installed, please make sure the phantomjs executable can be found via the PATH variable.
Quitting from lines 208-214 (tiler.Rmd) 
Error: processing vignette 'tiler.Rmd' failed with diagnostics:
cannot open the connection
--- failed re-building ‘tiler.Rmd’

SUMMARY: processing the following file failed:
  ‘tiler.Rmd’

Error: Vignette re-building failed.
Execution halted