Adding initial OpenAPI 3.0 support, Scala 2.11 file upload fix, adding missing import in http4s

Adding initial OpenAPI 3.0 support, Scala 2.11 file upload fix, adding missing import in http4s

Included issues:

• #181 Adding missing import for "ci" strings
• #185 Fixing compilation for file uploads in 2.11
• #177 Initial OpenAPI v3 support (Models and parser only, no new features)

Contributors:

• @blast-hardcheese
• fthomas/scala-steward
• @stanislav-chetvertkov
• @countfloyd
• @andreaTP

Adding models-only generator, permitting LocalDate QS args, fixing http4s path encoding bug

Adding models-only generator, permitting LocalDate QS args, fixing http4s path encoding bug

Included issues:

• #167 Adding Models kind
• #168 Adding an implicit Show[LocalDate]
• #170 Fixing encoding bug for http4s path segments

Contributors:

• @blast-hardcheese
• @calvinbrown085
• @griffio

Full status parsing for akka-http clients, http4s root path bugfix

Full status parsing for akka-http clients, http4s root path bugfix

Included issues:

• #165 http4s server generator handle root path
• #152 Make akka-http clients handle all status codes and described entities

Contributors:

• @blast-hardcheese
• @OleksandrSamsonov

Workaround for akka-http FormData 500s/temp file deletion

Included issues:

• #159 Making akka-http FormData return 413 instead of 500, delete failed files
• #158 Abstracting companion objects in preparation for java support

Contributors:

• @blast-hardcheese
• @kelnos

Exposing better validation messages in akka-http clients/server

Included issues:

• #150 Exposing helpful error messages
• #156 Bumping sbt-pgp
• #157 Bumping kind-projector

Contributors:

• @blast-hardcheese
• fthomas/scala-steward

Continuing to support more languages, fixing x-scala-null-is-empty

Included issues:

• #139 Bumping to scalameta 4.1.0
• #142 Moving more framework-specific logic into Free
• #145 Fixing bug in x-scala-empty-is-null for snake-cased parameters

Contributors:

• @blast-hardcheese
• @sullis
• @stanislav-chetvertkov
• @kelnos

Starting work to support other languages, handling unexpected status codes in http4s

Included issues:

• #136 Language abstraction
• #137 Handling unexpected status codes in http4s

Contributors:

• @blast-hardcheese
• @cponomaryov

Bumping circe and http4s

Included issues:

• #132 Updating http4s to 0.19.0
• #134 Updating circe to 0.10.1

Contributors:

• @blast-hardcheese
• @sjbog
• @cponomaryov

route sorting, OPTIONS, making BuildTracingFields overridable

Included issues:

• #125 Sorting generated routes to avoid unnecessary changes
• #126 Adding OPTIONS support
• #129 Making BuildTracingFields overridable

Contributors:

• @blast-hardcheese
• @nickfun
• @easel

Polymorphic responses and array form parameters

Included issues:

• #43 Missing Support for ComposedModels
• #89 Submitting a list of a form parameter is not supported
• #122 Guardrail doesn't support Array type for Form Params

Contributors:

• @dpblh
• @blast-hardcheese
• @charles-rumley
• @berkus