This commit replaces Spring Boot's basic dependency management support
with separate dependency management plugin. This has a number of
benefits including:
1. A Maven bom can be used rather than a custom properties file
2. Dependency management is applied transitively rather than only to
direct dependencies
3. Exclusions are applied as they would be in Maven
4. Gradle-generated poms are automatically configured with the
appropriate dependency management
Closes gh-2133
Update all starter POMs to remove commons-logging dependencies that are
not longer required when using the Spring Boot Gradle plugin.
Mainly reverts code from 196f92bd42
See gh-1047
Update all relevant starter POMs to include a `spring-core` dependency
with an exclusion on `commons-logging`. This prevents `commons-logging`
and `jcl-over-slf4j` from both being on the classpath.
Also add enforcer rules to ensure that commons-logging doesn't sneak
back in, and that there is no dependency convergence. (some additional
libraries were required in spring-boot-dependencies)
Tested with a sample maven project as well as using the `spring jar`
command.
Fixes gh-985
