Document WebSocket exclusions that are required when using Jetty 8

Closes gh-1969
Add metadata for logging.level

Closes gh-1992
Add metadata for info.*

Closes gh-1993
Haromonize configuration keys to lowercase hyphen
Add a plain JPA sample application

Closes gh-1761
Note that @IntegrationTest and @WebAppConfiguration can be used with Spock

Closes gh-1908
Merge branch '1.1.x'
Make TestInterceptor thread-safe

Previously, TestInterceptor used an int to keep a count of how often
it had been called. The count was incremented on one thread and
read on another thread. This lead to intermittent test failures as the
field was not declared volatile and a stale value would sometimes be
returned.

This commit updates TestInterceptor to use an AtomicInteger that's
held in a final field. This ensures that getCount() will not return
stale values and also ensures that the count can safely be incremented
concurrently.

Closes gh-1997
Allow the user to opt-out of anonymous access restrictions for /health

By default, when /health is accessed anonymously, the details are
stripped, i.e. the response will only indicate UP or DOWN. Furthermore
the response is cached for a configurable period to prevent a denial
of service attack.

This commit adds a configuration property,
endpoints.health.restrict-anonymous-access, that can be set to false
to allow full anonymous access to /health. When full access is
allowed, the details will be included in the response and the response
will not be cached.

Closes gh-1977
Document restrictions when /health is accessed anonymously

Closes gh-1978
Fix broken link to the MVC section of the Spring reference docs

Closes gh-1998
Merge branch '1.1.x'
Escape backslashes in .properties examples of setting internal-proxies

In a properties file, a backslash is used as an escape character for
the line terminator sequence to allow values to be split across
multiple lines. When a backslash is used elsewhere they're stripped
out of the property's value.

This commit updates .properties-based examples for configuring
server.tomcat.internal-proxies to escape the backslahes so that they
are retained in the property's value at runtime.

See gh-1989
Add a note explaining that double backslashes are unnecessary in YAML

Closes gh-1989
Merge branch 'gh-1989' into 1.1.x
Merge branch '1.1.x'
Use and wait for a latch to check that the interceptor is called

Spring MVC drives the postHandle method on any interceptors after the
response has been sent to the client. This meant that there was a
race between the test receiving the response and asserting that the
interceptor had been driven and Spring MVC driving the interceptor.

This commit updates the interceptor to use a CountDownLatch to track
whether or not it's been called. The test now waits for up to 30
seconds for the latch to be decremented.

Closes gh-1997
Only hide /health details if the app is actually secure

Also gives the user the option to override (by setting
endpoints.health.sensitive=false).

Fixes gh-1977 in a slightly different way
Check if managementServerProperties.getSecurity() is not null

before checking isEnabled(). It is explicitly constructed as null
in ManagementServerProperties to prevent class not found errors
at runtime when Security is not on the classpath.

Fixes gh-2003, fixes gh-2004
Remove double “and” from DataSourceInitializer’s javadoc