Issue

• Content-Type is not found in the header of Ceilometer alarm

When the option 'alarm-action' of Ceilometer was set as http URL, the contents did not include.

The header we confirmed was the following:

POST./v2/alarms/f9aa6b12-abb4-4491-abcc-32907bf99eec/notify.HTTP/1.1
Host:.10.43.108.80:2049
Content-Length:.314
Accept-Encoding:.gzip,.deflate,.compress
Accept:./
User-Agent:.python-requests/1.1.0.CPython/2.7.5.Linux/3.10.0-121.el7.x86_64

{"current":."alarm",
"alarm_id":."f9aa6b12-abb4-4491-abcc-32907bf99eec",
"reason":."Transition.to.alarm.due.to.1.samples.outside.threshold,.most.recent:.0.231666666667",
"reason_data":{
"count":.1,
"most_recent":.0.23166666666666663,
"type":."threshold",
"disposition":."outside"
},
"previous":."insufficient.data"}