Add ability to modify request options of then-request

[sn00pee]

Need the ability to set the timeout option in then-request options, so made an addition requestOptions param in the query

[SylRob]

I checked the then-request options.
there are half of them that are not fit for "GET" request.
And most of them does not have an echo in the "SSI simulator" that this loader try to do.

I think there are 2 options :

1 - we just add a timeout options.
If you need more options maybe you can list them with some use case / example.

2 - we need all the options right now.
then we need to set the possibility to choose "POST" or "GET" in the requests.
but this need use case / example also. Like "there are some dev server that request an Auth cookie
in order to fetch/read the files", etc...

what do you think ?