Resource Server Jwt Support

Introducing initial support for Jwt-Encoded Bearer Token authorization
with remote JWK set signature verification.

High-level features include:

- Accepting bearer tokens as headers and form or query parameters
- Verifying signatures from a remote Jwk set

And:

- A DSL for easy configuration
- A sample to demonstrate usage

Fixes: gh-5128
Fixes: gh-5125
Fixes: gh-5121
Fixes: gh-5130
Fixes: gh-5226
Fixes: gh-5237

samples/boot/oauth2resourceserver/spring-security-samples-boot-oauth2resourceserver.gradle

@@ -0,0 +1,13 @@
+apply plugin: 'io.spring.convention.spring-sample-boot'
+
+dependencies {
+	compile project(':spring-security-config')
+	compile project(':spring-security-oauth2-jose')
+	compile project(':spring-security-oauth2-resource-server')
+
+	compile 'org.springframework.boot:spring-boot-starter-web'
+	compile 'com.squareup.okhttp3:mockwebserver'
+
+	testCompile project(':spring-security-test')
+	testCompile 'org.springframework.boot:spring-boot-starter-test'
+}