Upgrade deprecated Query implementation to ContentChildren

[mko]

The deprecated Query and ViewQuery annotations have been replaced by ContentChildren and ViewChildren respectively. The resultant implementation is slightly different.

Old Query implementation:

    constructor(protected el: ElementRef,@Query(TabPanel) tabPanels: QueryList<TabPanel>) {
        tabPanels.changes.subscribe(_ => {
            this.tabs = tabPanels.toArray();
            let selectedTab: TabPanel = this.findSelectedTab();
            if(!selectedTab && this.tabs.length) {
                this.tabs[0].selected = true;
            }
        });
    }

New ContentChildren implementation:

    @ContentChildren(TabPanel) tabPanels: QueryList<TabPanel>;
    constructor(protected el: ElementRef) {
        this.tabPanels.changes.subscribe(_ => {
            this.tabs = this.tabPanels.toArray();
            let selectedTab: TabPanel = this.findSelectedTab();
            if(!selectedTab && this.tabs.length) {
                this.tabs[0].selected = true;
            }
        });
    }

And the imports change from Query to ContentChildren.

[mko]

Note: This is for RC6 compatibility.

[cagataycivici]

Doing this at constructor fails though with undefined at this.tabPanels, so using afterContentInit as doc suggests.