Improve dsl exception readability by double quoting names
of classes, properties, and methods mentioned in the exceptions.
Since property names are often lowercase strings (like 'find' or
'environment'), it can be very hard to distinguish a
property name from general exception information in the
error message (especially for someone new to MuranoPL).
This commit improves this situation, by explicitly highlighting
(quoting) the property in question.
Change-Id: Ic9b099818d558b07a38bada56a53d669f5a9299f
aeb9dca1c8