1.9.0

* ignore everything but official contracts for npm

* add tests to npm package

* remove truffle migrations stuff

* remove seemingly unused npm dependency

* clean up dependencies

* Make ERC827 methods payable

* Suppress linter errors

* Add some ERC827 payable tests

* Remove failOnBuy method from MessageHelper

* Fix linter warning

* Fix tests

* Update ERC827.sol to not use function overloading

* updated tests for erc827 function name changes

* fixed broken test

* removed findMethod from erc827 tests that is no longer necessary

Job is allowed to fail, and is run just for information purposes

* Increase test coverage to 93% #549

* cover missing AllowanceCrowdsale branch

* improve Heritable coverage

* fix lint errors

* proper equal assert

* address review comments

* remove unneeded const definitions and imports

* use assertRevert

* reword scenario description

* Increase test coverage to 93% #549

* cover missing AllowanceCrowdsale branch

* improve Heritable coverage

* fix lint errors

* proper equal assert

* address review comments

* remove unneeded const definitions and imports

* use assertRevert

* reword scenario description

* move HIGH_GOAL constant to the scope where it's used

* remove const at top level

* address review comments

* feat: implement bouncer contracts

* fix: rename Bouncer to SignatureBouncer

* Add StandardBurnableToken implementation

BurnableToken that extends from StandardToken and adds a
burnFrom method that decrements allowance. Equivalent to
a transferFrom plus burn in a single operation.

* Return event object from expectEvent helper

* Add comment on Approval event in burnFrom function

* Improvements on burnable token tests

- Inject initial balance as a parameter to the behaviour
- Use expectEvent helper for assertions on events
- Use chai bignumber for numbers
- Change to bdd-style assertions

* fix: clean up solium linting errors

* fix: make various contracts natspec compliant

* fix: this.balance deprecated; convert to address(this).balance

* fix: contract.call deprecated and switch to gasleft()

* fix: ignore empty block rule project-wide

* fix: add ignore cases for the rest of the linting warnings

* Update to ganache-cli v6.1.0 and truffle v4.1.0

* Update to stable version of ganache-cli

* fix: update event emission warning

- Fix event emission warnings for solidity 4.21 after truffle has been
updated to use this version

* fix pr review comments

* update to truffle v4.1.5

* update package-lock

* add additional emit keywords

* update solidity-coverage to 0.4.15

* update to solium 1.1.6

* fix MerkleProof coverage analysis by testing through wrapper

* change version pragma to ^0.4.21

* fix solium linting errors