Switch back to using Web3.Provider, not Web3Provider in internal classes

src/web3_wrapper.ts

@@ -2,15 +2,14 @@ import * as _ from 'lodash';
 import * as Web3 from 'web3';
 import * as BigNumber from 'bignumber.js';
 import promisify = require('es6-promisify');
-import {Web3Provider} from './types';
 
 export class Web3Wrapper {
     private web3: Web3;
-    constructor(provider: Web3Provider) {
+    constructor(provider: Web3.Provider) {
         this.web3 = new Web3();
         this.web3.setProvider(provider);
     }
-    public setProvider(provider: Web3Provider) {
+    public setProvider(provider: Web3.Provider) {
         this.web3.setProvider(provider);
     }
     public isAddress(address: string): boolean {
@@ -24,7 +23,7 @@ export class Web3Wrapper {
         const nodeVersion = await promisify(this.web3.version.getNode)();
         return nodeVersion;
     }
-    public getCurrentProvider(): Web3Provider {
+    public getCurrentProvider(): Web3.Provider {
         return this.web3.currentProvider;
     }
     public async getNetworkIdIfExistsAsync(): Promise<number|undefined> {