Closes gh-3913

Exclude spring-boot-starter-validation since those jars are provided
by the container.

Update the spring-boot-autoconfigure POM so that
jackson-module-parameter-names is optional.

See gh-3804

The parameter names module allows users of Java 8 that have compiled
their code with the -parameters option to avoid the name for
annotations to map the json onto constructor and method parameters
with the names of the parameters being used instead.

This commit adds auto-configuration for the module that will only
be enabled when running on Java 8.

Closes gh-3804

See gh-3900

Previously, dev tools would restart the application when any .class
file changed. This included test classes. This commit updates the
default excludes to ignore any classes with a name that ends in 
Test.class or Tests.class.

Closes gh-3900

For the character encoding filter to work, it's vital that it sets
the request's encoding before any other filters attempt to read the
request. This commit updates the order of
OrderedCharacterEncodingFilter to be HIGHEST_PRECEDENCE and improves
the existing test to check that the ordering is as required.

Closes gh-3912

Closes gh-3902

The recommended usage for the java executable is:

    java [-options] -jar jarfile [args...]

This commit updates the default launch script to match this recommended
usage by moving -jar to be the last option, after both the
disableJarChecking system property and any JAVA_OPTS.

Closes gh-3930

Closes gh-3913

* pr/3967:
  Polish Javadoc

Closes gh-3967

Closes gh-3943

See gh-3964

 - Rename local variable to avoid shadowing field with the same name
 - Add a test to verify that local.mongo.port is set on the parent
   context

Closes gh-3955

Previously, a StackOverflowError would occur when using a random port
for embedded mongo as the logic for propagating the property up the
context hierarchy would repeatedly use the leaf context's parent.

This commit updates the logic to look to see if the current context
has a parent, only calling the method again if it does.

Closes gh-3956

* pr/3946:
  Polish tests

Closes gh-3946

Update SpringBootServletInitializer with a registerErrorPageFilter flag
that can be used to disable ErrorPageFilter registration.

Fixes gh-3603

Update ErrorPageFilter to only handle errors when `response.sendError`
has been called. This should allow custom @ExceptionHandlers to
completely handle errors and return custom status codes without
triggering the "Cannot forward to error page" log message.

The Javadoc for sendError states:

  "The server defaults to creating the response to look like an
   HTML-formatted server error page containing the specified message"

Where as setStatus states

  "This method is used to set the return status code when there is
   no error "

Fixes gh-2745

Update `spring-boot-sample-tomcat-jsp` to include endpoints that trigger
exceptions. Primarily to aid testing of the ErrorPageFilter.

See gh-2745

* pr/3936:
  Polish contribution
  Expose actuator endpoints for flyway and liquibase

Closes gh-3936

Update the samples to expose the relevant actuator endpoint.

Closes gh-3935

Closes gh-3944

Closes gh-3940