JS API for querying RCDB

[DraTeots]

Use case 1:

RCDB web site should accept JSON object with request:

1. conditions name to get
2. query
3. run range

And get json object containing values with it:

Example request:

{
 "query": "@is_production and even_count>1M",
 "run_min": 20000,
 "columns_to_get": ["event_count", "target_name", "beam_current"],
}

Example of response:

{
"result":
 [
   {"run":20000, "event_count": 1873843563,   "target_name": "DIAMOND",     "beam_current": 100.2  },
   {"run":20001, "event_count": 3453497345,   "target_name": "DIAMOND",     "beam_current": 101.2  }
 ]
}