Bootified Spring Boot webmvc quickstart

Hi @jstrachan and @davsclaus,

James added to `process-spring-boot-bom` POM information needed to perform the release (SCM info, etc). I therefore refactored Spring Boot Webmvc Quickstart to use `process-spring-boot-bom` as a parent. This way this quickstart will be in sync with the idiomatic approach to the Spring Boot configuration, where end-user should only import BOM and don't care about the proper version of Spring Framework, Spring Boot, Spring Data and all the other dependencies provided by Spring BOM (note that I removed all the explicit versions declarations from the POM).

The main issue we had here was the fact that fabric8 BOM provides `spring.version` property with value `3.x` which overrides the same property from the Spring Boot BOM (as parent POM properties overrides those defined in imported BOMs). That's why Spring Boot quickstarts can't have main fabric8 BOM as a parent (and the reason why I created  `process-spring-boot-bom`).

Please let me know if that approach is OK with you.

Sorry for being POM-nazi here ;) , but I want to be sure that end-users can use our Spring Boot quickstarts the same way the Spring reference describes it. Otherwise folks will complain that they are trying to use their existing Spring Boot application configurations, but they got versions conflicts.

Cheers.