Allow module directories to be named with more valid characters ensuring that module names in fragment meta-data are correct

When modules are named "silverstripe-something" the regex fails to pickup the correct module name. I couldn't find unit tests for this part of the ConfigManifest, there appears to be no testing of the parsing of the yml files (addYAMLConfigFile). It would be more effort than I have time for to write tests covering this part of the system, apologies.