[api] add HTTP put and HTTP delete support for apirequest

keep the old SeafileApiRequest::METHOD_POST and SeafileApiRequest::METHOD_GET,
and add several new methods, METHOD_DELETE, METHOD_PUT, METHOD_POST_V2 and
METHOD_PUT_V2.

1. METHOD_DELETE is responsible for HTTP delete method, similiar to METHOD_GET

2. METHOD_PUT is responsible for HTTP put method, similiar to METHOD_PUT

3. METHOD_POST_V2 and METHOD_PUT_V2 are refined post/put action.
    they pass the data which is set by SeafileApiRequest::setData
    to the HTTP body, and pass params in the HTTP header,
    instead of the old behaviour.