refactor(Gallerize): Use MutationObserver instead of AfterContentChecked
refactor(Gallerize): Use MutationObserver instead of AfterContentChecked

Use `MutationObserver` instead of `ngAfterContentChecked` to prevent infinite loop in default change detection strategy, closes #70
MurhafSousli/ng-gallery,MurhafSousli/ng-gallery,MurhafSousli/ng-gallery