Reading chemkin files in binary mode

To make it platform independent, changing the reading
from 'r' to 'rb'
Modifying mode in which chemkin file is read

This is to make it make it platform independent
Raise an appropriate error when molecule can't be drawn.

Makes error on website for visualizing chemkin file more debuggable.
Merge branch 'master' of github.com:GreenGroup/RMG-Py
Merge remote-tracking branch 'GreenGroup/master'