CRM-14798 - Case Type Name

(Note: I expect this to be a little controversial / require some discussion
or changes.)

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

 1. The admin 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
 4. The admin goes back to rename his file to match the double-munged version.

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. 

This PR fixes the handling of case-type name in the UI -- and gives the
admin/developer more meaningful freedom to specify the name of the case-type
without any back/forth over filenames.