Separate ERC721Mintable (#1365)

* separate part of ERC721Mintable into ERC721MetadataMintable

* remove mint and burn from 721 tests

* Fixed linter error.

* fix ERC721 mint tests

* Minor fixes.

(cherry picked from commit 744f567f40)

contracts/token/ERC721/ERC721MetadataMintable.sol

@@ -0,0 +1,32 @@
+pragma solidity ^0.4.24;
+
+import "./ERC721Metadata.sol";
+import "../../access/roles/MinterRole.sol";
+
+
+/**
+ * @title ERC721MetadataMintable
+ * @dev ERC721 minting logic with metadata
+ */
+contract ERC721MetadataMintable is ERC721, ERC721Metadata, MinterRole {
+  /**
+   * @dev Function to mint tokens
+   * @param to The address that will receive the minted tokens.
+   * @param tokenId The token id to mint.
+   * @param tokenURI The token URI of the minted token.
+   * @return A boolean that indicates if the operation was successful.
+   */
+  function mintWithTokenURI(
+    address to,
+    uint256 tokenId,
+    string tokenURI
+  )
+    public
+    onlyMinter
+    returns (bool)
+  {
+    _mint(to, tokenId);
+    _setTokenURI(tokenId, tokenURI);
+    return true;
+  }
+}