Use '-1' to disable management port

Update `EndpointWebMvcAutoConfiguration` to use '-1' to indicate that
the management context should be disabled. This brings consistency
between the server settings and the management settings and allows '0'
to be used to pick a random port.

Fixed gh-311
Polish
Document Listener/Initializer changes

Fixes gh-312
Update ErrorMvcAutoConfiguration for Spring 4

Update ErrorMvcAutoConfiguration thymeleaf condition to use the
`spring4` package.

Fixes gh-310
Restore active profile logic and support `+`

Restore the previous `spring.profiles.active` logic effectively
reverting commit 37069d9. This ensures that active profiles defined in
a higher `PropertySource` replace those lower down.

In addition, add support for a `+` prefix that can be used to indicate
that a profile should be added to the active set.

For example:

	# application-prod.properties
	spring.profiles.active=+proddb,+prodmq

Fixed gh-308, gh-309