Allow curlopt keyword at httpclient request level.
Allow curlopt keyword at httpclient request level.

Now you can set curlopt on kore.httpclient at both the
global httpclient object level and individual requests.

Eg:

client = kore.httpclient("https://kore.io",
    curlopt={
        kore.CURLOPT_VERBOSE: 1
    }
)

status, body = await client.get(
    curlopt={
        kore.CURLOPT_VERBOSE: 0
    }
)

jorisvink/kore,jorisvink/kore