Registration contract for generalized shutter

[ylembachar]

See EPIC shutter-network/shutter-api#1 for the full specification.

• Deploy new contract that allows registering identities and their time-based triggers
• Clients need to submit their payment during registration
• Payments are directly sent to the contract and can be withdrawn by the contract’s owner
• Allows for balance withdrawal (can implement the Ownable pattern)
• Possibility to adjust the price per registration (start with zero fees)