Simplify RxSocialLogin.** methods into one methods

[WindSekirun]

Affect Version: 1.1(Remove) Currently there are separate methods for each platform, so there is a lot of work to be done when adding a new platform.

In addition, we already provide platform information in LoginResultItem, so we do not need any distinction in Observable.

[WindSekirun]

Older methods will deprecated in 1.1.0, and remove in 1.2.0

[WindSekirun]

Changes Notice

This notice contains breaking changes on public methods

Remove in 1.1

• RxSocialLogin.facebook
• RxSocialLogin.kakao
• RxSocialLogin.naver
• RxSocialLogin.line
• RxSocialLogin.twitter
• RxSocialLogin.google
• RxSocialLogin.github
• RxSocialLogin.linkedin
• RxSocialLogin.wordpress
• RxSocialLogin.yahoo
• RxSocialLogin.vk
• RxSocialLogin.windows
• RxSocialLogin.disqus
• RxSocialLogin.foursquare
• RxSocialLogin.twitch
• FacebookLogin.toObservable()
• KakaoLogin.toObservable()
• NaverLogin.toObservable()
• LineLogin.toObservable()
• TwitterLogin.toObservable()
• GoogleLogin.toObservable()
• GithubLogin.toObservable()
• LinkedInLogin.toObservable()
• WordpressLogin.toObservable()
• YahooLogin.toObservable()
• VKLogin.toObservable()
• WindowsLogin.toObservable()
• DisqusLogin.toObservable()
• FoursquareLogin.toObservable()
• TwitchLogin.toObservable()

New in 1.1

• RxSocialLogin.result(login: RxSocialLogin) - convert into Observable
• RxSocialLogin.result(vararg login: RxSocialLogin) - convert login into List of Observable and merge into one observable.

[WindSekirun]

Due to the issue (#29), existing methods cannot be retained and existing methods are deleted.