Added libnlopt-dev to R installation for AFNI
Added libnlopt-dev to R installation for AFNI

Compilation of R, required for AFNI, was throwing an error related to libnlopt - unable to download the source. This lib is also available as a binary object via apt-get. So, instead of compiling this lib, we now download it.
kaczmarj/neurodocker,kaczmarj/neurodocker