Update health endpoint sensitive flag in docs
Provide a way to opt-in to endpoint enablement

Update AbstractEndpoint so that the `enable` property is optional and
when it not specified the `endpoints.enabled` property will be used.

This allows users to switch the way that endpoints are enabled. Rather
than opting-out specific endpoint enablement the `endpoints.enabled`
property can be set to `false` and specific endpoints can be opted-in.

Fixes gh-2102
Setup MongoMappingContext setInitialEntitySet

Update MongoDataAutoConfiguration to set the MongoMappingContext
initialEntitySet by scanning for @Document or @Persistent classes
from AutoConfigurationPackages.

Fixes gh-2107
Polish
Make DEFAULT_PROTOCOL public

Fixes gh-2110
Merge branch '1.1.x'
Fix "heath" misspellings
Next development version
Next development version
Fixup version numbers following release
Fixup version numbers following release
Restore use of management.health.*.enabled keys

The move of health.* keys to management.health.* broke them as they
are not defined as configuration keys and `ManagementServerProperties`
is strict on the whole management namespace.

This commit updates the tests to actually include that properties class
and relax the "ignoreUnknownFields" condition so that extra attributes
can be defined on the "management" namespace.

Fixes gh-2115
Fix management endpoint without Spring Security

The method 'injectIntoSecurityFilter' added In 3c1e48c assumes that
Spring security is in the classpath so any management endpoints that are
deployed on a different port requires Spring Security all the sudden.

This commit separates the creating of the EndpointHandlerMapping in two
mutually exclusive @Configuration: one that is triggered if Spring
Security is not in the classpath and one that is triggered if Spring
Security is in the classpath. The latter apply the security filter in the
endpoint mapping if it exists.

Fixes gh-2124
Improve property target name

Previously, non camel case properties were wrongly resolved, i.e.
getFOO() leading to a 'f-o-o'. While unusual, underscores can also be
added to a property name. In that case, the hyphen should not be added
as the binder consider this to be a single "word". Typically setFoo_Bar
on the "something" prefix is mapped using "something.foo_bar".

All these cases are now handled properly, generating the target name that
the binder expects.

Fixes gh-2118
Properly guard ManagementSecurityAutoConfiguration

ManagementSecurityAutoConfiguration fully relies on the presence of a
web environment, yet the configuration class itself was not guarded by
`@ConditionalOnWebApplication` (while nested config where).

This turned out to be a problem for command-line applications using
spring security (i.e. CRaSH integration).

Fixes gh-2112
Properly document health indicator config

Health indicator configuration keys have moved from the health.* to the
management.health.* namespace. This commit makes sure that these are
documented properly in 1.1.x as well.

See gh-2118
Merge branch '1.1.x'
Add explicit reference to health.*

Health indicator configuration keys have moved from the health.* to the
management.health.* namespace. This commit adds an explicit reference
to the previous location.

See gh-2128
Polish indent
Merge branch '1.1.x'