Remove / from thermal conductivity units in input spec

[ecoon]

Slashes in input spec parameter names break some xml parsers, at least in python, and need to be escaped. This makes them hard to work with for external tools, even though they are valid in C++/Teuchos::ParameterList.

Currently the only ones I know of are in the thermal conductivity parameters: [W/(m-K)] units, which should get changed to [W m^-1 K^-1]

[lipnikov]

I am curious, what is a need to specify SI units explicitly?

[ecoon]

Just for user documentation. In native spec we don't have the ability to introduce a "units=XXX" to our Parameter object, and not having units in input files that get read by users means our users make mistakes and assume incorrect units.