Add complex crowdsale example #331

contracts/examples/crowdsale/SampleCrowdsale.sol

+pragma solidity ^0.4.11;
+
+import "../../crowdsale/CappedCrowdsale.sol";
+import "../../crowdsale/RefundableCrowdsale.sol";
+import "./SampleCrowdsaleToken.sol";
+
+/**
+ * @title SampleCrowdsale
+ * @dev This is an example of a fully fledged crowdsale that incorporates
+ * ability to finalize sale and checks for both cap and goal.
+ */
+contract SampleCrowdsale is CappedCrowdsale, RefundableCrowdsale {
+
+  function SampleCrowdsale(uint256 _startBlock, uint256 _endBlock, uint256 _rate, uint256 _goal, uint256 _cap, address _wallet)
+    CappedCrowdsale(_cap)
+    FinalizableCrowdsale()
+    RefundableCrowdsale(_goal)
+    Crowdsale(_startBlock, _endBlock, _rate, _wallet)
+  {
+    require(_goal <= _cap);
+  }
+
+  function createTokenContract() internal returns (MintableToken) {
+    return new SampleCrowdsaleToken();
+  }
+
+}
\ No newline at end of file

contracts/examples/crowdsale/SampleCrowdsaleToken.sol

+pragma solidity ^0.4.11;
+
+
+import "../../token/MintableToken.sol";
+
+
+/**
+ * @title SampleCrowdsaleToken
+ * @dev Very simple ERC20 Token that can be minted.
+ * It is meant to be used in a crowdsale contract.
+ */
+contract SampleCrowdsaleToken is MintableToken {
+
+  string public constant name = "Sample Crowdsale Token";
+  string public constant symbol = "SCT";
+  uint256 public constant decimals = 18;
+
+}