Replaced Solium in favor of Solhint (#1575)

* Adding solhint, working on style fixes.

* Upgraded to solhint 1.5.0.

* Removed all references to Solium

* Updated mocks to make the pass the new linter rules.

* Reformatted the .solhint.json file a bit.

* Removed Solium configuration files.

* Remove Solium dependency.

* Add comment explaing disabled time rule in TokenVesting.

* Revert to the old (ugly?) style.

* Revert SignatureBouncerMock style.

* Fix ERC165InterfacesSupported interface.

contracts/mocks/OwnableMock.sol

@@ -2,4 +2,6 @@ pragma solidity ^0.5.0;
 
 import "../ownership/Ownable.sol";
 
-contract OwnableMock is Ownable {}
+contract OwnableMock is Ownable {
+    // solhint-disable-previous-line no-empty-blocks
+}