Add OAS 3.0 support

[postatum]

Fixes #59, #69
Adds OAS 3.0 support (beta). Also updates AMF to version 4.0.3.

This should be released as version 0.5.0 because AMF update adds breaking changes.
Below are release notes.

---

Added OAS 3.0 support (beta)

Methods names and interfaces are identical to those of OAS 2.0 but reside in a WebApiParser.oas30 namespace for JS and webapi.Oas30 for Java.

Updated AMF to to 4.0.3

The updated caused following changes. See AMF 4.0.3 release notes for more details.

Below are security model changes described in detail.

Security API change (BREAKING):

Changed type of WebApi, EndPoint, Operation field security and input type of method withSecurity from ParametrizedSecurityScheme[] to SecurityRequirement[].

Where obj is an instance of one of - WebApi, EndPoint, Operation:

Before:

obj.security: ParametrizedSecurityScheme[]
obj.withSecurity(security: ParametrizedSecurityScheme[])

Now:

obj.security: SecurityRequirement[]
obj.withSecurity(security: SecurityRequirement[])

Migration:

obj.security[0] -> obj.security[0].schemes[0]

OAuth2 Settings API change (BREAKING):

New OAuth2Settings fields added:

OAuth2Settings.flows: OAuth2Flow[]
OAuth2Settings.withFlows(flows: OAuth2Flow[]): this

Most of OAuth2Settings methods and fields[1] moved to OAuth2Flow.

[1] authorizationUri, accessTokenUri, flow, refreshUri, scopes, authorizationGrants, withAuthorizationUri, withAccessTokenUri, withFlow, withRefreshUri, withScope.

Updated Scala plugins:

• sbt-scalajs-crossproject 0.6.0 -> 0.6.1
• sbt-scalajs 0.6.25 -> 0.6.29
• sbt-scoverage 1.5.1 -> 1.6.0

[abhikt48]

is there anyway to get snapshot version of 0.5.0 or are you planning to release soon? Please suggest.