libwebsockets

test server align rxbuf with permessage deflate rx buf size

Add a test html button that will send 9KB of junk to confirm it

https://github.com/warmcat/libwebsockets/issues/480

permessage-deflate now checks the protocol rx buffer size for being
>=128, if not, permessage-deflate is disabled on that connection.

If it is >=128 but less than the zlib decompress buffer size, the
zlib decompress buffer size for that connection is reduced to the
nearest power of two of the protocol rx buf size.

To test this, dumb_increment is left violating the >= 128 rx buffer
size and permessage-deflte can be seen to be disabled on his
connections in the test html.

Signed-off-by: Andy Green <andy@warmcat.com>