/i/alert/save

For request query param "alert_config", it is a JSON string. If this object contains "_id" property,
it will update existing alert, otherwise will create a new alert.

For example:

alert_config = {
    "_id": "59c4ab3cb722e037767f25bb",
    "alertName": "New Crash",
    "alertDataType": "crash",
    "alertDataSubType": "New crash occurence",
    "period": "every 5 minutes",
    "alertBy": "email",
    "enabled": true,
    "selectedApps": [
                "55a3e43b16129b942651127d2",
        "55a8fd212612129926557187",
        "55af42eb6550e69a26966183"
    ],
    "compareDescribe":"New crash occurence ",
    "alertValues":["573afc01f5a2dd12368c30990"],
    "createdBy":"573afc01f5a2dd12368c30990"
}