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.
@Scottmitch I believe this is incorrect.  The initial window size is only supposed to affect stream windows, not the connection window. See https://tools.ietf.org/html/draft-ietf-httpbis-http2-15#section-6.9.2

    A SETTINGS frame cannot alter the connection flow control window.