Combine the Utility and Common packages

[milesj]

Both of these packages do something similar, they provide shared functionality for other packages. In almost all cases, all other packages require either one of these, or both of these, so it might make sense to combine them into a single package.

Plan of action:

• Move Common interfaces to Common\Contract
• Move Utility classes to Common\Utility
• Move Utility\State to Common\State
• Remove Utility package