This commit commit adds restdocs and stub generators and initiate
a reference guide for Initializr.
Most of the controller tests now use MockMvc via a custom version
of the MockMvcClientHttpRequestFactory (from spring-test). The
snippet names are auto-generated in the form
<HttpMethod>/<path>[/queries(/<name-value)*][/headers](/name-value)*]
when there is a comma-separated value in a header it is
abbreviated as <first-value>.MORE.
Wiremock stubs are generated in the same form under
snippets/stubs (with ".json" as the
file extension).
The controller tests that stayed as full stack use a different
base class AbstractFullStackInitializrIntegrationTests.
A long JSON body can be broken out into separate snippets
for each field (or rather a list of fields supplied by the
user). This feature was already used with hard-coded snippets
in the wiki.
See gh-295
