Move Github issues to cpp-ethereum, solidity, remix

[bobsummerwill]

We need to migrate bugs from webthree-umbrella to cpp-ethereum, solidity or remix as appropriate. Anything related to AlethZero or Mix should just be closed.

Something I have noted is that the labels for cpp-ethereum are a bit weird and different.

They probably just need updating to match the ones we have here.

[bobsummerwill]

Done