fix(dateadapter): moment dates not in utc format

Moment DateAdapter should create dates in utc format to avoid time zone
collisions when passing date to servers

Closes angular#7167

src/material-moment-adapter/adapter/moment-date-adapter.spec.ts

@@ -143,7 +143,7 @@ describe('MomentDateAdapter', () => {
   });
 
   it('should create Moment date', () => {
-    expect(adapter.createDate(2017, JAN, 1).format()).toEqual(moment([2017,  JAN,  1]).format());
+    expect(adapter.createDate(2017, JAN, 1).format()).toEqual(moment.utc([2017,  JAN,  1]).format());
   });
 
   it('should not create Moment date with month over/under-flow', () => {
@@ -164,6 +164,10 @@ describe('MomentDateAdapter', () => {
     expect(adapter.createDate(100, JAN, 1).year()).toBe(100);
   });
 
+  it('should create Moment date in utc format', () => {
+    expect(adapter.createDate(2017, JAN, 5).isUTC()).toBeTruthy();
+  });
+
   it("should get today's date", () => {
     expect(adapter.sameDate(adapter.today(), moment()))
         .toBe(true, "should be equal to today's date");

src/material-moment-adapter/adapter/moment-date-adapter.ts

@@ -130,7 +130,7 @@ export class MomentDateAdapter extends DateAdapter<Moment> {
       throw Error(`Invalid date "${date}". Date has to be greater than 0.`);
     }
 
-    let result = moment({year, month, date}).locale(this.locale);
+    let result = moment.utc({year, month, date}).locale(this.locale);
 
     // If the result isn't valid, the date must have been out of bounds for this month.
     if (!result.isValid()) {