Use an embed HornetQ broker by default

This commit changes the default behavior of the HornetQ auto
configuration. Prior to this commit, an embedded broker was only
started when it was requested explicitly by a configuration option.

This is inconsistent with the ActiveMQ support and boot favors the
easiest route. If the necessary classes are available, HornetQ is
embedded in the application by default.

Fixes gh-1029
Fix docs in ServletInitializer
Switch to a matches-none filter for security.basic.enabled=false

There were some residual issues to do with the changes to the implementation
of security.basic.enabled=false. It was a good idea to have a filetr chain
triggered by the flag being off because it smooths the way for user-defined
filter chains to use the Boot AuthenticationManager (as a first step at least),
but it wasn't a goog idea to add any actual secuity features to that filter.
E.g. if it has HSTS then even an app like Sagan that has some secure endpoints
that it manages itself and the rest is unsecured has issues because it can't
accept connections over HTTP even on unsecure endpoints.

TODO: find a way for security.ssl_enabled=true to apply to only the user-
defined security filter (maybe not possible or worth the effort, since they
can inject a SecurityProperties if they need it?).

See gh-928
Default Compile tasks to use UTF-8 encoding

We also convert the SpringBootPlugin to be .groovy to ease defaulting
the encoding to UTF-8. We do not make the file any "more groovy" to leave
this to a distinct commit.
Make SpringBootPlugin more Groovy

- Remove ;
- Remove unnecessary public modifiers
- Remove unnecessary .class suffixes

Fixes gh-1032
polishing
Attempt to fix test failures on CI

This commit is an attempt to fix the build failures with the HornetQ
tests and relates to #1034
Rationalize the Reactor autoconfig

It didn't make sense not to do anything at all if a Reactor @Bean
was detected, so now we only back off creating the rootReactor if
one is present.
Added Janino to BOM.
Merge pull request #1016 from hekonsek/bom-janino

* bom-janino:
  Added Janino to BOM.
Add a note regarding dependency overriding

Fixes gh-958
Fix broken links in the documentation
Merge branch '1.0.x'
Auto-generate auto configuration classes tables
Add tests to verify starter dependencies when used with Gradle

We've had problems with the starters when used with Gradle. They have
been pulling in commons-logging (#987) and the wrong version of Spring
(#1028) due to Gradle's different exclusion and dependency resolution
semantics.

This commit adds some integration tests that use Gradle's tooling API
to take each starter in turn and build a Gradle project that depends
upon it. The build looks at the transitive dependencies and checks
that neither commons-logging nor any Spring modules with the wrong
version are present.