Remove unused dependencies

[Celebrate-future]

@edureka-git Hi, I am a user of project com.edurekademo.tutorial:addressbook:2.0. I found that its pom file introduced 30 dependencies. However, among them, 6 libraries (20%) have not been used by your project (the redundant dependencies are listed below). This PR helps com.edurekademo.tutorial:addressbook:2.0 lose weight :) I have tested the revised configuration in my local environment. It is safe to remove the unused libraries.

Best regards

Redundant dependencies----

 com.vaadin:vaadin-themes:jar:8.0.0.alpha2:compile com.vaadin.external.flute:flute:jar:1.3.0.gg2:compile org.codehaus.jackson:jackson-core-asl:jar:1.9.4:compile com.vaadin:vaadin-compatibility-client-compiled:jar:8.0.0.alpha2:compile org.codehaus.jackson:jackson-mapper-asl:jar:1.9.4:compile org.codehaus.jackson:jackson-jaxrs:jar:1.9.4:compile