Proposal to make mandatory Params in Command

Currently, the Command structure has an optional Params field. This
field, along with the existance of a "void" data type, has been found to
be ambiguous. The proposal is to remove the optional modifier in the
params field, to eliminate this ambiguous usage.

Change-Id: If631cc15656882fca90e94e7ad9b2b6b9d46fc66