when TABLE_KEY_FIELD in SEND_FIELDS

[iap]

I have a problem when TABLE_KEY_FIELD in SEND_FIELDS,
the TABLE_KEY_FIELD does not sent by station.py.

A work-around for this is to upper case the TABLE_KEY_FIELD. then it
works.

Like this:
## does not work
ROCKET_ENTITIES = {
"Document":{
MODE: SEND,
TABLE_NAME:"Document",
TABLE_KEY_FIELD: "id",
SEND_FIELDS:["id","content"],
}

## works
ROCKET_ENTITIES = {
"Document":{
MODE: SEND,
TABLE_NAME:"Document",
TABLE_KEY_FIELD: "ID",
SEND_FIELDS:["id","content"],
}