Update dockerfile

nlopt does not get built automatically by the installation of nloptr for
some reason. So we install nlopt for ubuntu before running packrat. Also,
a recent version of R is needed for the rgdal version in packrat.lock to
install, so we add tag 3.4.3 to the r-base starting image.

eric-figs/Dockerfile

@@ -1,9 +1,10 @@
-FROM r-base
+FROM r-base:3.4.3
 MAINTAINER Eamon O'Dea <[last name without apostrophe]35@gmail.com>
 
 RUN apt-get update && apt-get install -y -q --no-install-recommends \
 libcurl4-openssl-dev \
 libgdal-dev \
+libnlopt-dev \
 libproj-dev \
 libpng-dev \
 libpoppler-cpp-dev \