CRM-14798 - CRM_Case_XMLRepository - Don't double-munge the case-type name.

CRM-14798 - CRM_Case_XMLRepository - Don't double-munge the case-type name.

Prior to this commit, the naming for a case-type flowed more or less
like:

1. User makes up a display-name (title/label)
2. That title is munged via CRM_Utils_String::titleToVar to produce a machine-name
3. That machine-name is munged via CRM_Case_XMLProcessor::mungeCaseType to produce a file-name

As we begin allowing more varied dataflows for managing CaseType XML files
and CaseType DB records, it becomes more important for the naming behavior
to intuitive.