Removed BreakInvariantBounty.

Added sender parameter to initializers using msg.sender.

Initialization improvements

Merging OZ 2.0.0.rc3

(cherry picked from commit 308e5e9c)

(cherry picked from commit 43ebb4fc)

* signing prefix added

* Minor improvement

* Tests changed

* Successfully tested

* Minor improvements

* Minor improvements

* Revert "Dangling commas are now required. (#1359)"

This reverts commit a6889776.

* updates

* fixes #1371

* Removed extra whitespace

(cherry picked from commit f3888bb0)

* signing prefix added

* Minor improvement

* Tests changed

* Successfully tested

* Minor improvements

* Minor improvements

* Revert "Dangling commas are now required. (#1359)"

This reverts commit a6889776.

* updates

* fixes #1356

* Removed extra semicolon.

(cherry picked from commit c87433e0)

* separate part of ERC721Mintable into ERC721MetadataMintable

* remove mint and burn from 721 tests

* Fixed linter error.

* fix ERC721 mint tests

* Minor fixes.

(cherry picked from commit 744f567f)

Merge OpenZeppelin 2.0 with initializer functions

update Math.sol path

* Fixed a broken payment test

* In PR template, npm run lint:fix, not lint:all:fix

* In SplitPayment test, replaced an await-in-loop with Promise.all

(cherry picked from commit b79196f9)

* fix: refactor sign.js and related tests

* fix: remove unused dep

* fix: update package.json correctly

* Add missing tests to ECRecovery

* fix lint

* Reorganize the tests

* Reuse signature

* fix static errors

* Apply suggestions by @frangion and @nventuro

* Remove only

* More suggestions

* Remove unnecessary max-len

* remove only

(cherry picked from commit 75c0a59b)

* add test for msg.data too short

* fix test to hit that branch

* Update SignatureBouncer.test.js

(cherry picked from commit 1a4e5346)