Certain blocks are incompatible with XNet

[PolyacovYury]

Discussion started here: https://github.com/McJtyMods/XNet/issues/437

So, the problem is the following. XNet doesn't provide facing when doing hasCapability checks, since Advanced Connectors are able to access all sides of the block. This, however, creates problems when trying to connect certain Embers' machines (e.g. Alchemy Tablet, Centrifuge).

Basically - certain machines return false for hasCabapility(capability, null) when they probably shouldn't - null stands for "any side", as far as I understand.