Collection manager API: consider allowing user to pass `history=false` for any bucket type

When creating or updating a collection, and passing `history=false`, the server returns HTTP status code 400 and this error message:

{"errors":{"history":"Bucket must have storage_mode=magma, not couchstore"}} 

This is a problem because in the collections manifest returned by the server for a non-magma bucket, every collection has a `history` field with value `false`. This makes round-tripping difficult, since propagating that "history=false" back into a create/update request triggers the 400 result.

Proposal: relax the argument validation so the user can always pass "history=false". Return the 400 code only if the user passed `history=true` and the storage engine is not magma.

Alternate proposal: In the collections manifest, only include the "history" field if the bucket uses magma.