MINOR: runtime: add acl_files and acl_files_entries

MINOR: add file (full path) attribute to SSL certificate model

MINOR: global: add default ciphersuites

Review comments

BUG/MINOR: resolvers: fix field definitions

RELEASE: New version 2.0.0 of the models

In this release:
- updated go.mod file with updated dependencies and /v2 suffix
- upgraded go to 1.14
- upgraded swagger to 0.23.0

FEATURE/MINOR: server, bind: add allow-0rtt option

BUG/MINOR: validation: ease regex validations

Ease regex validation on backend_switching_rule to allow using
variables for backend name. Also remove regex check for cookie in
backend and defaults to allow adding extra cookie parameters.

MEDIUM: Add information models

MINOR: backends: add hash-type option