Release v2.17.0

The official docker release for this release can be pulled from

    quay.io/dexidp/dex:v2.17.0

Notes:

* Dex finally offers a user info endpoint. While this doesn't expose any
  more information than is included in the ID tokens, it allows for using
  Dex in integrations that demand such an endpoint.
* With this release, the Linkedin connector is usable again!

Features:

* Add UserInfo endpoint (#1473, @alindeman, @jackielii, and @fjbsantiago)
* Linkedin: Update to use v2 APIs (#1460, @tanmaykm)
* server: add metrics for CORS handlers (#1429, @tsuna)
* OIDC: Add option to hit the optional userinfo endpoint (#1433, @jacksontj)
* OIDC: Make userID configurable (#1448, @cappyzawa)
* OIDC: Make userName configurable (#1459, @flarno11)
* GitLab: support for group whitelist (#1436, @bonifaido)

Bug fixes, misc changes:

* Print appropriate error when listing connectors fails (#1443, @deric)
* Bitbucket docs: update permission requirements (#1435, @bonifaido)
* Round out logging interface with functions for all levels (#1432, @alindeman)
* Fix typo in SAMLConnector interface (#1430, @mkontani)
* travis: replace golang 1.10 and 1.11 with 1.12 (#1457, @srenatus)
* OIDC: truely ignore "email_verified" claim if configured that way (#1456, @srenatus)
* MAINTAINERS: remove ericchiang@ (#1478, @ericchiang)