Return open claims alongside bounties in API

[martinklepsch]

Currently we send bounties and claims separately which led to issues like #432.

Similar to how claims are injected into owner-bounties (see code below) we should include claims with the API response. At the time of writing this "joining" is handled by a client side subscription.

open-bounty/src/clj/commiteth/routes/services.clj

Lines 64 to 71 in ece5333

	(defn ^:private enrich-owner-bounties [owner-bounty]
	(let [claims (map
	#(update % :value_usd usd-decimal->str)
	(bounties-db/bounty-claims (:issue_id owner-bounty)))
	with-claims (assoc owner-bounty :claims claims)]
	(-> with-claims
	(update :value_usd usd-decimal->str)
	(assoc :state (bounties/bounty-state with-claims)))))

Ultimately we will also need to implement server-side pagination as outlined in #250.