Changed dict comprehension to support Python 2.6.
Changed dict comprehension to support Python 2.6.

The syntax used here is only valid in Python 2.7 or later. We want to
support Python 2.6 as well, hence the change.

KEHANG/RMG-Py,comocheng/RMG-Py,comocheng/RMG-Py,chatelak/RMG-Py,pierrelb/RMG-Py,nickvandewiele/RMG-Py,pierrelb/RMG-Py,nyee/RMG-Py,chatelak/RMG-Py,nyee/RMG-Py,enochd/RMG-Py,nickvandewiele/RMG-Py,faribas/RMG-Py,faribas/RMG-Py,enochd/RMG-Py,KEHANG/RMG-Py