Change bean name of ContentNegotiatingViewResolver

Fixed gh-428
Change exception message for missing Thymeleaf templates

Fixes gh-424
Add MultipartConfig to DispatcherServlet by default

RC4 added a ServletRegistrationBaen for teh DispatcherServlet and we
didn't register a MultipartConfigElement if one was present.

Fixes gh-427
Consider subtypes in exception error page mapping

Fixes gh-417
Switch off debug in secure sample

Fixes gh-438
Tweak external config file loading to support additional profiles

Profiles set with Environment.setActiveProfiles() (rather than
spring.profiles.active) *before* any config files are processed, are
treated as "additional" (to the ones supplied in spring.profiles.active
from all sources, files and System properties included).

Fixes gh-429
Use redis starter in sample
Use java.io.tmpdir instead of /tmp

Fixes gh-441
Special case for root of classpath resource in archive

This turns out to affect JPA, but only because it looks for a URL for the
root of the classpath using ClassLoader.getResource("") which barfs in
an app launched from an executable JAR. It's easy to make a special case
for "" in the class loader, so I went ahead and did that. Possibly need
to think what the implication of getResources("") is as well (not
tested in an app yet).

Fixes gh-420
Remove assumption in test about /tmp location
polishing documentation
Change explicit bean type to concrete NamedParameterJdbcTemplate

Fixes gh-447
Use org.springframework.boot groupId in spring-boot-samples

Use org.springframework.boot instead of ${project.groupId}
groupId in order to make it easier to use spring-boot-samples
modules as a starting point for new projects.
Fix typo
fixup yaml codeblock
Allow non-string return from health query
fix link to install.txt

Explicitly link to install.txt in source repo to avoid issues on projects.spring.io with a broken relative link
... also fix this for rendered markdown on GH itself :-)
Added testWhileIdle etc.

Fixes gh-463
Add templates/** to list of default includes for CLI jars

Boot promotes the use of a templates directory for housing view
templates. Include this directory by default when building a jar file
from a CLI app.

Fixes #455
More care taken with management.contextPath

The management.contextPath property should now be respected in a
secure application, whether or not the management.port is different.

Added some test cases in the sample to verify.

Fixes gh-469