Webhooks input plugin

Feature request: Webhooks input plugin (Something like generic HTTP/JSON)

GELF HTTP Input requires a specific json formating that you often can't set from the sender (Juniper Mist & Meraki for example)

Example incoming webhook:

{
"topic": "device-updowns",
"events": [
{
"ap": "123456789012",
"ap_name": "ua-ap41-01",
"org_id": "06e214fb-b5b2-4934-abf2-lk1j23lk4j12",
"reason": "unknown",
"site_id": "1e3c0949-a0df-4cb3-asdf-aasdfasdfd",
"site_name": "Uppsala",
"timestamp": 1575012212,
"type": "AP_RESTARTED"
}
]
}