Remove Tasks and Payments

[kronosapiens]

Closes #1126

Removes Tasks and Payments from the core contracts. Specifically:

• Deletes ColonyTask.sol and ColonyPayments.sol and removes all references to them from the rest of the contracts
• View functions remain, as does the ability to remove funds from existing Tasks and Payments
• Migrates the test suite away from Tasks and towards Expenditures as a way of giving out tokens and reputations
• For the reputation tests, migrates to direct reputation rewards and penalties

For simplicity, the tests have been left otherwise untouched, meaning that we still give out reputation in the same way as we did when we used Tasks (i.e. three recipients, penalties, etc).

A bit unrelated, but this PR also does the following:

• Updates the OneTxPayment extension to set the globalClaimDelay to 0

[area]

Out of a meeting I've just had with Arren/Jack: OneTxPayment should work even if there is a non-zero global claim delay for expenditures.

[area]

What do you think of, in finishUpgrade of OneTxPayment:

• Check if we (the extension) has root permission in the colony.
• If not, no further actions and return
• If it does, award itself arbitration permission in root domain

This obviously doesn't capture all scenarios, but will mean that the front-end team don't have to worry about handling the adding of the permission on upgrade, based on how the extension is currently used.

[kronosapiens]

@area works for me. Do you want me to add it or you?

[area]

What do you think of, in finishUpgrade of OneTxPayment:

* Check if we (the extension) has root permission in the colony.

* If not, no further actions and return

* If it does, award itself arbitration permission in root domain

This obviously doesn't capture all scenarios, but will mean that the front-end team don't have to worry about handling the adding of the permission on upgrade, based on how the extension is currently used.

This doesn't actually work, OneTxPayment is only awarded Funding and Administration currently, so I'll remove the commit.