Include collectives in organization(s) and sponsor(s) member stats

[mkurz]

While working on #502 I found out that when fetching organisations/sponsors for the banner the type that will be fetched from the api gets set to ORGANIZATION and COLLECTIVE:

opencollective-images/src/server/lib/graphql.js

Lines 205 to 209 in f2ca296

	if (backerType.match(/sponsor/i) || backerType.match(/organization/i)) {
	type = 'ORGANIZATION,COLLECTIVE';
	} else {
	type = 'USER';
	}

When fetching the member stats (for the badge) you only count organizations however, but not collectives:

opencollective-images/src/server/lib/graphql.js

Lines 110 to 111 in f2ca296

	if (backerType.match(/sponsor/i) || backerType.match(/organization/i)) {
	count = res.Collective.stats.backers.organizations;

Isn't that inconsistent?
Either you should never take into account collectives or add them to the stats as well (what my pull request does).
If you think the former is better, feel free to close this pull request, I can add another one removing COLLECTIVE from the first code snippet.