add .importNetCdf; add Pietro Franceschi as contributor
add NetCDF test case
finalize CDF support
install suggested package RNetCDF for travis-ci
install RNetCDF dependencies for travis-ci via apt-get
prepend installation of RNetCDF dependencies for travis-ci
add install_aptget libnetcdf for travis-ci
test only if RNetCDF is available
0.6 release