Add Google IMA plugin

[Elecash]

We need to add Google IMA plugin.

Suggested API is to follow ng1 version.

<vg-ima-ads 
        network="6062" 
        unit-path="iab_vast_samples" 
        companion="companionAd" 
        companion-size="[728, 90]" 
        ad-tag-url="http://pubads.g.doubleclick.net/gampad/ads?sz=640x480&iu=/124319096/external/ad_rule_samples&ciu_szs=300x250&ad_rule=1&impl=s&gdfp_req=1&env=vp&output=vmap&unviewed_position_start=1&cust_params=deployment%3Ddevsite%26sample_ar%3Dpremidpost&cmsid=496&vid=short_onecue&correlator=" 
        skip-button="<div class='skipButton'>skip ad</div>">

https://github.com/videogular/videogular/blob/master/app/scripts/com/2fdevs/videogular/plugins/vg-ima-ads/vg-ima-ads.js