Mark the Bit, Unsigned and Integer traits as 'static

[tspiteri]

Closes #170.

[tspiteri]

While adding 'static, I found that Bit and Unsigned both have Copy + Default supertraits but Integer does not. Does it make sense to also add Copy + Default to Integer for consistency, or was the omission intentional?

[paholg]

It was not intentional. That would be appreciated!

[tspiteri]

Done.

[paholg]

Thanks!