* Add BigNumber support to expectEvent/inLogs (#1026)
* switched direct logs array check to expectEvent method in AllowanceCrowdsale.test.js
* Refactor expectEvent.inLogs function to use simple value number check
* Introduced should.be.bignumber method to compare BigNumber values
* Destructure transaction object to extract logs field
(cherry picked from commit 947de54cee)
* Extract standard token behaviuor to reuse it in other tests
* Add opt in ERC20 migration contract
* Make migration contract not to depend from standard token
* Changes based on feedback
* Improve MigratableERC20 inline documentation
* move behaviors to behaviors directory
* refactor MigratableERC20 into ERC20Migrator
* fix errors
* change expectEvent to support multiple events with same name
* fix tests
* update documentation
* rename MigratableERC20 files to ERC20Migrator
* move to drafts
* test beginMigration
* rename to ERC20Migrator
* missing semicolon (╯°□°）╯︵ ┻━┻
* add non-zero check
* improve documentation based on review comments
* improve test descriptions
* improve docs
* add getters
* fix contract
* improve tests
* 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
