* Basic idea
* Fine tuning idea
* Add comments / tidy up Crowdsale base class
* fixed TimedCrowdsale constructor
* added simple crowdsale test
* added HODL directory under home to store unused contracts. ugly hack to solve Crowdsale selection in tests, better way?
* Capped no longer inherits from Timed, added capReached() method (replacing hasEnded())
* added SafeMath in TimedCrowdsale for safety, CHECK whether it is inherited from Crowdsale
* several fixes related to separating Capped from Timed. functions renamed, mocks changed. Capped tests passing
* added TimedCrowdsaleImpl.sol, TimedCrowdsale tests, passed
* added Whitelisted implementation and test, passed.
* removed unnecessary super constructor call in WhitelistedCrowdsale, removed unused dependencies in tests
* renamed UserCappedCrowdsale to IndividuallyCappedCrowdsale, implemented IndividuallyCappedCrowdsaleImpl.sol and corresponding tests, passed.
* homogeneized use of using SafeMath for uint256 across validation crowdsales. checked that it IS indeed inherited, but leaving it there as per Frans suggestion.
* adding questions.md where I track questions, bugs and progress
* modified VariablePriceCrowdsale, added Impl.
* finished VariablePrice, fixed sign, added test, passing.
* changed VariablePrice to IncreasingPrice, added corresponding require()
* MintedCrowdsale done, mock implemented, test passing
* PremintedCrowdsale done, mocks, tests passing
* checked FinalizableCrowdsale
* PostDeliveryCrowdsale done, mock, tests passing.
* RefundableCrowdsale done. Detached Vault. modified mock and test, passing
* renamed crowdsale-refactor to crowdsale in contracts and test
* deleted HODL old contracts
* polished variable names in tests
* fixed typos and removed comments in tests
* Renamed 'crowdsale-refactor' to 'crowdsale' in all imports
* Fix minor param naming issues in Crowdsale functions and added documentation to Crowdsale.sol
* Added documentation to Crowdsale extensions
* removed residual comments and progress tracking files
* added docs for validation crowdsales
* Made user promises in PostDeliveryCrowdsale public so that users can query their promised token balance.
* added docs for distribution crowdsales
* renamed PremintedCrowdsale to AllowanceCrowdsale
* added allowance check function and corresponding test. fixed filename in AllowanceCrowdsale mock.
* spilt Crowdsale _postValidatePurchase in _postValidatePurchase and _updatePurchasingState. changed IndividuallyCappedCrowdsale accordingly.
* polished tests for linter, salve Travis
* polished IncreasingPriceCrowdsale.sol for linter.
* renamed and polished for linter WhitelistedCrowdsale test.
* fixed indentation in IncreasingPriceCrowdsaleImpl.sol for linter
* fixed ignoring token.mint return value in MintedCrowdsale.sol
* expanded docs throughout, fixed minor issues
* extended test coverage for IndividuallyCappedCrowdsale
* Extended WhitelistedCrwodsale test coverage
* roll back decoupling of RefundVault in RefundableCrowdsale
* moved cap exceedance checks in Capped and IndividuallyCapped crowdsales to _preValidatePurchase to save gas
* revert name change, IndividuallyCapped to UserCapped
* extended docs.
* added crowd whitelisting with tests
* added group capping, plus tests
* added modifiers in TimedCrowdsale and WhitelistedCrowdsale
* polished tests for linter
* moved check of whitelisted to modifier, mainly for testing coverage
* fixed minor ordering/polishingafter review
* modified TimedCrowdsale modifier/constructor ordering
* unchanged truffle-config.js
* changed indentation of visibility modifier in mocks
* changed naming of modifier and function to use Open/Closed for TimedCrowdsale
* changed ordering of constructor calls in SampleCrowdsale
* changed startTime and endTime to openingTime and closingTime throughout
* fixed exceeding line lenght for linter
* renamed _emitTokens to _deliverTokens
* renamed addCrowdToWhitelist to addManyToWhitelist
* renamed UserCappedCrowdsale to IndividuallyCappedCrowdsale
