SCIFIOToolCommands: add API to get name

Added API to get the name for each SCIFIOToolCommand. A default
implementation in the abstract layer will default to using the class
name in lower case to preserve previous behavior.

This will allow tools to be created with arbitrary (and ideally more
informative) class names, without being tied to their display name when
running SCIFIOTools.
SCIFIOTools: use command name API

Updated SCIFIOTools to index commands on their command name, instead of
relying on their class name.

Based on the default implementation of this method, current commands
should have identical names.
SCIFIOTools commands: return command name

Added implementations for the commandName method to exisiting commands,
to prevent confusion in case these files are ever moved.