Approve without body (sagemath#11)

* approve_without_body initial

* add missing positional arg

* nochmal

* issue 2

* Introduce SYNC_LABELS_BOT_TOKEN and fix issue 1

* Fix in gh_cmd because of mark_as_ready

* Ignore trigger of bot

* Ignore actor's reviews on needs review

* dismiss_bot_reviews and refrain from removing labels

* fix broken call of review_by_actor

* add get_review_requests

* consistent use of state versus status

* add full stops in comments