Add oauth 2.0 state field as a parameter to requestAccessUri

[bschwind]

@shunjikonishi please review

In order for an application to properly check the oauth state parameter, it needs to generate the field by itself and pass it in to the OAuth URL generation function. This is similar to how facebook4j handles it: http://facebook4j.org/javadoc/facebook4j/auth/OAuthSupport.html#getOAuthAuthorizationURL(java.lang.String, java.lang.String)

sbt test was failing for me before I made any changes, so I'm not sure if this breaks any tests or not.

[shunjikonishi]

@bschwind fix me

Sorry. sbt test doesn't work now. Because some tests depends on GitHub account status.
I was aware it at my previous fixing, but not investigated well.

About this PR, please modify method signature to use Option.

def requestAccessUri(state: Option[String] = None, scope: String*) = {

because your implementation might cause dangerous situation.
For example, basic use case of requestAccessUri is like this.

     val url = oauth.requestAccessUri("user", "repo")

Above code specifies "user" and "repo" for scope.

However, after your modification, above code means state="user", scope="repo"!!!

and to make matter worse, there is no chance for developers to be aware of this bug.

To use Option and default parameter, I think we can avoid this situation.

[bschwind]

@shunjikonishi Unfortunately I don't think Scala allows that kind of method signature

a parameter section with a `*'-parameter is not allowed to have default arguments
def requestAccessUri(state: Option[String] = None, scope: String*) = {

Do you think I should just make an overloaded method that takes a state parameter instead?

[bschwind]

Actually, overloading will also be confusing, so I think a new method with a different name is probably the best way to approach this.

[shunjikonishi]

Ah, sorry. please remove default parameter.

def requestAccessUri(state: Option[String], scope: String*) = {

We can detect the problem by compile error, when we update lib.

[bschwind]

@shunjikonishi does anyone outside of givery use this library?

[shunjikonishi]

I don't know. But probably not. (This library is not published to maven-central or typesafe)

[bschwind]

@shunjikonishi I think it's better to not touch the original method and just add an overloaded version. That way we won't break any older users of this library, and we can start using the state parameter.

[shunjikonishi]

I'll merge this.