Added surface tension for fluids covered in Mulero, JPCRD, 2014 (http://scitation.aip.org/content/aip/journal/jpcrd/43/2/10.1063/1.4878755)

Signed-off-by: Ian Bell <ian.h.bell@gmail.com>
Implemented the viscosity correlation for n-Heptane of Assael, JPCRD, 2014 (http://scitation.aip.org/content/aip/journal/jpcrd/43/2/10.1063/1.4875930) and testing data

Signed-off-by: Ian Bell <ian.h.bell@gmail.com>
Updated reference for Heptane

Signed-off-by: Ian Bell <ian.h.bell@gmail.com>
hashes.json file gets saved in the right place

Signed-off-by: Ian Bell <ian.h.bell@gmail.com>
Small modifications to the conductivity of Heptane

Signed-off-by: Ian Bell <ian.h.bell@gmail.com>
Merge branch 'master' of https://github.com/coolprop/coolprop