Fixes gh-500

Fixes gh-507

Fixes gh-499

Change working since test dependencies cannot easily be replaced.

Remove quote-marks from internal documentation links and instead favor
italics.

* docs:
  Review first 8 parts of the doc

This commit mostly fixes typos but also improves slightly specific
areas, adding links when it make sense.

See gh-499

Currently Spring Boot fails in Java 1.6 on Mac OS X due to the
"tools.jar" being integrated into classes.jar in the Apple version of
Java 6.

Apple fixed this with Java 7, but we should still support Java 6. We had
to roll back to maven-plugin-plugin 3.1 to make this work with Java 6
and 7.

All tests pass with Java 6 and Java 7.

Fixes gh-492

Fixes gh-495

Remove README files that have been since been migrated to the reference
documentation. Also updated remaining markdown files to asciidoctor to
save having a mix of different formats.

Fixed gh-503

Port Add Maven example for Tomcat 8 from markdown to asciidoc.
(originally from commit 15372cb7)

Port documentation originally added in commit b56bd0a1

Fixes gh-490

Fix test failure caused by URL -> Url rename in
commit 22e397cd

Fixed gh-295

Add a "cloud deployment" section to the Spring Boot reference
manual.

See gh-295

Copy the existing markdown How-to readme content to the user manual,
converting to asciidoc.

See gh-295

See gh-295

Generate html, pdf and epub documentation using asciidoctor+docbook.

See gh-295

See gh-482

This is quite a big step, but I think it helps a lot. Since Spring
Boot always creates an AuthenticationManager if it doesn't find one
already registered, it makes sense to also make it into a @Bean.
Spring Security does not register its AuthenticationManager by
default though, so we have to do that for it if the user has created
one with an @Autowired AuthenticationManagerBuilder, but not registered
it as a @Bean.

Having the @Bean (marked @Primary to prevent issues with @Autowired)
makes it easier to reason about what Spring Boot has done for you, and
easier to default in simple use cases to the boot-created
AuthenticationManager. For example, if I want an OAuth2 Authorization
Server with password grant, it makes total sense for the
AuthenticationManager for users to be the same as the @Primary one.
Now it is easy to set that up (just @Autowire it).

also adds another test.

...bean with no explicit @Bean DispatcherServlet. We still have to check
by bean name (slightly unfortunate, but we need to avoid instantiating
too early) so there's now another magic
bean name for the registration bean ("dispatcherServletRegistration")
that the user has to replace if he wants the registration without
defining a servlet @Bean

Fixes gh-482