Add accept methods into suggestions.
Add accept methods into suggestions.

Features are:
 - Admins can accept an aggregation instead of single suggestions. With this, for example, when admin wants to accept all suggestions for a domain, he can accept corresponding WebsiteURLSuggestionAggregation object.
 - Admins can also accept single suggestions.
 - When a suggestion is accepted, it creates corresponding tests if they are not created and removes itself from all aggregations and deletes itself.

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