Remove @EnableWebMvc from SwaggerConfig

[Aloren]

Remove @EnableWebMvc from org.springdoc.ui.SwaggerConfig as not needed for Spring Boot Web Mvc applications.

fixes #236 #150

[Aloren]

@springdoc probably smth is broken in configuration for sonar as the build fails with:

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-deploy-plugin:2.8.2:deploy (default-deploy) on project springdoc-openapi: Failed to deploy artifacts: Could not transfer artifact org.springdoc:springdoc-openapi:pom:1.2.20-20191223.174348-3 from/to ossrh (https://oss.sonatype.org/content/repositories/snapshots): Failed to transfer file https://oss.sonatype.org/content/repositories/snapshots/org/springdoc/springdoc-openapi/1.2.20-SNAPSHOT/springdoc-openapi-1.2.20-20191223.174348-3.pom with status code 401 -> [Help 1]

I've run all the tests locally and the build is green.

[springdoc]

Thank you @Aloren for your contribution.