Websocket connection header is case-insensitive

[emlove]

Description

This change makes the websocket connection header check case insensitive. Per RFC 6455, 4.2.1.4, this check should be case insensitive.

Motivation and Context

Not all websocket clients will send the connection header using the same case that Kodi is expecting. See aio-libs/aiohttp#1495.

How Has This Been Tested?

This has been tested by connecting to Kodi using Python's aiohttp v1.2.0, using the following test script:

import aiohttp
import asyncio

@asyncio.coroutine
def main(loop):
    client = aiohttp.ClientSession(loop=loop)
    ws = yield from client.ws_connect('ws://192.168.1.193:9090/jsonrpc')
    while True:
        msg = yield from ws.receive()
        if msg.type == aiohttp.WSMsgType.TEXT:
            print(msg)
        elif msg.type == aiohttp.WSMsgType.CLOSED:
            break
        elif msg.type == aiohttp.WSMsgType.ERROR:
            break

loop = asyncio.get_event_loop()
loop.run_until_complete(main(loop))

Screenshots (if appropriate):

Types of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the Code guidelines of this project
• My change requires a change to the documentation, either Doxygen or wiki
• I have updated the documentation accordingly
• I have read the CONTRIBUTING document
• I have added tests to cover my change
• All new and existing tests passed

[Montellese]

jenkins build and merge

[MartijnKaijser]

jenkins build this please