@Controller -> @RestController in docs

Fixes gh-652
/etc/bash_completion.d -> something else

I preferred /etc/bash_completion.d (since it mirrors the actual
preferred deployment of the scripts on my OS). Maybe the MacBoys
have a different point of view? Anyway the docs now point to the
actual script location.

Fixes gh-651
@Controller -> @RestController in README

Fixes gh-652 some more
Fixed minor mistakes

* your -> you're
* ask a questions -> ask a question

Fixes gh-653
Grammar etc. fixes in the docs

Fixes gh-654
Add enabled flag to RegistrationBean

Default to true but allow user to switch off a @Bean of type
Filter (for example) by wrapping it in a disabled registration.

Fixes gh-655
Now after starting application PID file will be created

Fixes gh-550
Add parent directory creation

Also tidied a few other things up (like not needing
SmartApplicationListener).

Fixes gh-550
Minor fixes in the docs
changed 'that can you can' to 'that you can' in Getting Started: 8. Introducing Spring Boot
Print MAVEN_OPTS=-noverify for copy-pasters
Remove return keyword from groovy examples in docs

Fixes gh-656
Add JAXB mini-example to howto

Fixes gh-646
Rename identifier in the howto so that it's unique
Re-order if blocks in RunMojo

Avoids loading a class if not needed, but doesn't seem to solve
any actual problems. I'll leave it in in case it helps later.

Testing gh-648
Extended documentation for applicaiton pid monitoring
Special case for deferred start based on Handler type

Fixes gh-673
Add support for .yaml file extensions

Apparently yaml.org prefers .yaml, but the internet seems
to be more aligned with .yml, so I guess we should support both
out of the box.

Fixes gh-675
Add spring.thymeleaf.contentType (defaults to HTML)

User can specify the content type in external properties now, optionally
ommitting the charset (since that is duplicated). If charset is not
appended by user Spring will do it.

Fixes gh-671
Expand Error Handling section in docs a bit

Fixes gh-513