#1783 rank0 to string prints name=, which creates problems in scripts

[Jeremy Faden]

Rank0 datasets have always been formatted as <name>=<value>, and this often causes problems with scripts which just want to check for a certain string value. I have scripts that have code that looks for the equals sign, and removes the label if one is found. I think this finally should be changed, to just <value>.</value></value></name>

[Jeremy Faden]

Perhaps this should be fixed on the 2017a branch as well. Another thought is that there be an official way to get the string representation of a rank0 dataset, similar to the DatumFormatter where you can indicate if there is an external context. This would allow existing codes to continue working, and can provide a more rigid definition of the method.