Add test for GRUU being preserved over ENUM
Don't do ENUM lookups on GRUUs, even if the user part is numeric
Improve UT commenting
Merge pull request #755 from Metaswitch/gruu

[Reviewer: Mike] Don't do ENUM lookups on GRUUs, even if the user part is numeric
Put back some whitespace errors to fix up some merge conflicts
Merge pull request #756 from Metaswitch/whitespace_errors

[No review required] Put back some whitespace errors to fix up some merge conflicts