Migrate userXML to GrandMaster

[kakwok]

For #110

• Only CfgCVSBasePath and MasterSnippetList(ie the file name of grandMaster) should remain in LV1's userXML.
• All other userXML accesses will refer to the "grandMaster" file
• Putting a bunch of userXML accesses in EventHandler complicates things because LV2s have empty userXML. Shall we move those out to LV1EventHandler?

[sethcooper]

• Shouldn't we go into error if the CfgCVSBasePath or the MasterSnippet list can't be found (i.e., on catching an exception)? I don't really like relying on defaults, nor on just sticking a warning message in the log. Of which there are many already. Speaking of which...
• Please cut down on logger.info and logger.warn
• I don't really understand what the return "" are doing in the getHCALuserXMLelementContent and getNamedUserXMLelementAttributeValue functions
• Otherwise, assuming it's been tested, it seems fine

[kakwok]

getHCALuserXMLelementContent and getNamedUserXMLelementAttributeValue has been re-directed to look for the grandMaster. If the file name of the grandMaster is missing, the two functions return ""

[kakwok]

-Removed the unused special snippets filenames from userXML, e.g. #139
-Handles no MasterSnippetList exception
-Move userXML from EventHandler to LV1EventHandler
-Add a switch to getHCALuserXMLelementContent and getNamedUserXMLelementAttributeValue so that they can access real userXML.

[kakwok]

Also closing #28