Added mechanism to pass arguments to client.

[gedex]

The first endpoint to use is boards, specifically actionsresource that accept various arguments. If approved, will add other endpoints that accept arguments.

Example

var args []*trello.Argument
args = append(args, trello.NewArgument("filter", "updateCard:idList"))
args = append(args, trello.NewArgument("since", "2016-02-01"))
args = append(args, trello.NewArgument("before", "2016-02-05"))

actions, err := board.Actions(args...) // query string will be ?before=2016-02-05&filter=updateCard%3AidList&since=2016-01-28

Resolves #15

[VojtechVitek]

Can we call it Arg?

[VojtechVitek]

This is really good addition, @gedex. What would you think about the following API?

type Args []Arg

args := trello.Args{{"filter", "updateCard:idList"}, {"before", "2016-02-05"}}
actions, err := board.Actions(args...)

actions, err := board.Actions(trello.Arg{"filter": "updateCard:idList"})

[klauern]

This is great, and something I was just thinking of adding. I merged this into my own fork and am using it. I fully support merging this or something like it.

[VojtechVitek]

@gedex any input on my last comment?

[fiatjaf]

Why trello.Arg instead of just map[string]string?

[fiatjaf]

Accepting a list of argument keypairs is a good idea that it can be of the form of variadic arguments, instead of requiring a nil for all calls for which you don't want to send arguments.

[VojtechVitek]

Why trello.Arg instead of just map[string]string?

The only benefit would be the possibility of defining methods on Args without breaking the API. For example, we could add validation/normalization methods on Args etc. It's map[string]string anyway behind the hood.

Accepting a list of argument keypairs is a good idea that it can be of the form of variadic arguments, instead of requiring a nil for all calls for which you don't want to send arguments.

Yes, it will be variadic and optional for sure.

[VojtechVitek]

I'm gonna merge and rename to Arg. Thank you for this contribution!

[gedex]

Apologies for late reply, been busy with works. Thanks for the merge @VojtechVitek.