Transfer replacement (#1962)

* Add Address.sendEther

* Add documentation to sendEther

* Add changelog entry

* Rename sendEther to sendValue

contracts/mocks/EtherReceiverMock.sol

@@ -0,0 +1,15 @@
+pragma solidity ^0.5.0;
+
+contract EtherReceiverMock {
+    bool private _acceptEther;
+
+    function setAcceptEther(bool acceptEther) public {
+        _acceptEther = acceptEther;
+    }
+
+    function () external payable {
+        if (!_acceptEther) {
+            revert();
+        }
+    }
+}