added uni-v2 condition and action

[hilmarx]

Created:

• Uniswap v2 Rate Condition
• Uniswap v2 Trade Action
• Cancel Task Receipt Script

Deployed:

• Aforementioned contracts
• ConditionTime on Mainnet

Fixed:

• Some bugs in old scripts

[gitpusha]

• Contracts don't seem to be verified on Etherscan
• getSysAdmin() is annoying because we should just use one PK for CLI on mainnet/testnets. Makes everything easier. In local tests we can use multiple wallets.
• There is a package-lock.json file which should be removed

In general we should clean up this repo and use only 1 deployment process.

I suggest we should redeploy all our contracts eventually using buidler-deploy as our deployments manager.

This will also allow us to verify all of them trivially on Etherscan.