Capitalize the 'Connection'='upgrade' header in request

[soulfly]

Hi guys,

I found that you use "Connection=upgrade" header when do WebSocket handshake
https://github.com/zwopple/PocketSocket/blob/master/PocketSocket/PSWebSocketDriver.m#L220

it's basically ok and conform to rfc6455

But the issue I have is that some servers expect this header as capitalized, e.g. "Connection=Upgrade"

for example, Tigase XMPP server does it this way
https://tigase.tech/projects/tigase-server/repository/revisions/master/entry/server/src/main/java/tigase/server/websocket/WebSocketXMPPIOService.java#L367

probably that's because in all rfc6455 examples it stays as capitalized, e.g.
https://tools.ietf.org/html/rfc6455#section-1.2

Are you able to do this change in this lib?
I do not see any issues with backward compatibility here

thank you