* 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.
* Now compiling in a separate directory using truffle 5.
* Ported to 0.5.1, now compiling using 0.5.1.
* test now also compiles using the truffle 5 hack.
* Downgraded to 0.5.0.
* Sorted scripts.
* Cleaned up the compile script a bit.
* Now only swapping when needed.
* Removed _addTokenTo and _removeTokenFrom
* Removed removeTokenFrom test.
* Added tests for ERC721 _mint and _burn
* _burn now uses the same swap and pop mechanism as _removeFromOwner
* Gas optimization on burn
* separate part of ERC721Mintable into ERC721MetadataMintable
* remove mint and burn from 721 tests
* Fixed linter error.
* fix ERC721 mint tests
* Minor fixes.
