Increase default buffer size for read/write operations

[korydraughn]

The following configuration properties need their values increased to make transfers between the user and the HTTP API faster (out of the box).

• max_number_of_bytes_per_read_operation
• max_number_of_bytes_per_write_operation

[trel]

i've found 8M to be good. can test that to find a better default.