Lyft SDK 2.0.0

2.0.0 Release of the Android SDK. (#20)

* [Deeplink] Change Deeplink parameter for ride type into an enum. (#13)

* Add RideType enum for Deeplinks

* Update ride type names for button enum

* Remove button's enum

* Fix tests

* Fix NPE

* [Networking] Check and reject responses returned with partial data (#14)

* Add interface

* Update response models

* Implement null check converter

* Update riderequest response models

* Implement methods to disallow null checking

* Remove dead links

* Update documentation

* Address PR comments (ApiFactory)

* Address PR comments (ICompleteData -> Validatable)

* [SDK] Update Gradle Dependency Versions (#16)

* Update Gradle + Android Gradle Plugin

* Update dependency versions

* Unused cleanup

* RxJava -> RxJava 2

* Bump Lyft SDK version

* Fix Lint

* Update travis

* [Networking] Remove User API. (#17)

* Remove UserApi

* Remove user access token

* Remove related models

* LyftPublicApi -> LyftApi

* LyftPublicApiRx -> LyftApiRx

* Factory method renames

* [Networking] Document nullable fields in network responses (#18)

* CostEstimate documentation

* Eta documentation

* Nearby Drivers

* Pricing Detail

* Ride types

* Update Cost

* Fix Mock API

* Update CHANGELOG

* [Ride Type] Fix enum string values to reflect correct server rend… (#19)

* Fix Lux SUV enum

* Update ride type display names to match endpoints values

* Stamp release date in CHANGELOG

* Update README