HTTP/2 Inbound Flow Control Connection Window Issues

Motivation:
The inbound flow control code was returning too many bytes to the connection window.  This was resulting in GO_AWAYs being generated by peers with the error code indicating a flow control issue.  Bytes were being returned to the connection window before the call to returnProcessedBytes. All of the state representing the connection window was not updated when a local settings event occurred.

Modifications:
The DefaultHttp2InboundFlowController will be updated to correct the above defects.
The unit tests will be updated to reflect the changes.

Result:
Inbound flow control algorithm does not cause peers to send flow control errors for the above mentioned cases.
This is the value that I think we want to keep.  We should rename this to `DEFAULT_INITIAL_CONNECTION_WINDOW_SIZE`.  When the connection state is created, it's initialized to `DEFAULT_WINDOW_SIZE`, same as streams ... however the first time the connection window is expanded, it will expand to this value.