Extension of Crowdsale contract where purchases can be paused and unpaused by the pauser role.
function _preValidatePurchase(address _beneficiary, uint256 _weiAmount) internal view
Validation of an incoming purchase. Use require statements to revert state when conditions are not met. Use super to concatenate validations. Adds the validation that the crowdsale must not be paused.
_beneficiary- Address performing the token purchase
_weiAmount- Value in wei involved in the purchase