Remove unused imports

And it changes code to use ES6 style import statements instead of
require.

Author: Seulgi Kim

src/command/create.ts

@@ -1,5 +1,3 @@
-import * as _ from "lodash";
-
 import { Context } from "../types";
 import { getAddressFromKey } from "../util";
 

src/command/delete.ts

@@ -1,5 +1,3 @@
-import * as _ from "lodash";
-
 import { CLIError, CLIErrorType } from "../error";
 import { Context } from "../types";
 import { findMatchingKey } from "../util";

src/command/import.ts

@@ -1,5 +1,4 @@
 import { SecretStorage } from "codechain-keystore";
-import * as _ from "lodash";
 
 import { Context } from "../types";
 import { getAddressFromKey } from "../util";

src/command/importRaw.ts

@@ -1,5 +1,4 @@
 import { PrivateKey } from "codechain-keystore/lib/types";
-import * as _ from "lodash";
 
 import { Context } from "../types";
 import { getAddressFromKey } from "../util";

src/util.ts

@@ -1,6 +1,6 @@
 import { Key } from "codechain-keystore/lib/types";
 import { AssetTransferAddress, PlatformAddress } from "codechain-primitives";
-import _ = require("lodash");
+import * as _ from "lodash";
 
 import { CLIError, CLIErrorType } from "./error";
 import { AccountType } from "./types";