Supporting node-mapnik

[springmeyer]

Node-mapnik has both header-only dependencies and pre-compiled dependencies. And quite a few of them - so it will be a good stress test to make sure things are working right (and is an important target for mason-js). Its mason-versions.ini will look like:

[headers]
protozero=1.6.1
boost=1.65.1
[compiled]
jpeg_turbo=1.5.1
libpng=1.6.28
libtiff=4.0.7
icu=57.1
proj=4.9.3
pixman=0.34.0
cairo=1.14.8
webp=0.6.0
libgdal=2.1.3
boost_libsystem=1.65.1
boost_libfilesystem=1.65.1
boost_libregex_icu57=1.65.1
freetype=2.7.1
harfbuzz=1.4.2-ft
mapnik=3.0.17

@millzpaugh - Can you add to your testing plan to develop support for this .ini?

[millzpaugh]

Noted. Thanks @springmeyer!