Saving metadata only saves/returns the last{key: value} pair

[DylanAllen]

Customers Version: 0.5.0-dev25

What were you trying to do?
Save customer metadata

What did you expect to see?
All properties passed to be saved.

What did you see?
Only the last property in the request body is being saved

How can we reproduce the problem?
PUT /customers/{customerID}/metadata
Request

{
   "metadata":{
      "keyone":"value",
      "keytwo":"valuetwo",
      "keythree":"valuethree"
   }
}

Response:

{
...
   "metadata":{
      "keytwo":"valuetwo"
   },
...
}