Migrate to buidler-aragon

[sohkai]

• Migrate each app (see original PR: Migrate official aragon apps to Buidler set up #1084)
  • Agent (PR: Agent: move to buidler #1092)
  • Finance (PR: Finance: Move to buidler setup #1109)
  • Token Manager (PR: Tokens: Move to buidler setup #1119)
  • Vault (PR: Vault: Move to buidler setup #1108)
  • Voting (PR: Voting: update to buidler 0.2.0 #1125)
• Upgrade aragonOS across all apps
• Fix tests (see below)
• Fix linting
• Fix any other anomalies

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Tests:

• WIP Fix Migrate vault to Buidler aragon-cli#1509 (vault)
  • Failing test: set up the default vault correctly to recover ETH from the kernel - ALSO FAILS ON MASTER
• WIP Fix Migrate agent to Buidler aragon-cli#1484 (agent)
  • Also runs vault tests, and as stated above, one of them fails - ALSO FAILS ON MASTER
• WIP Fix Migrate finance to Buidler aragon-cli#1483 (finance)
  • Three tests failing:
    • "can recover ETH using AragonApp#transferToVault" - ALSO FAILS ON MASTER
    • "fails when too many period transitions are needed"
      • fails, unless gas is set to 3e6 (ten times as much!)
      • passes in master with 3e5 gas, even if ganache-cli.sh is modified to use istanbul
      • Buidler currently has an issue where the fork cannot be modified (reported, fix soon)
      • Also fails when running npx buidler test --network localhost with a running ganache-cli instance with any fork.