Add custom Eclipse code formatter

Update Eclipse settings to make use of a custom Spring formatter
implementation. Using a custom formatter allows us to fix a couple of
issues with the version that shipped with Eclipse Mars.1 (Eclipse bugs

The custom formatter also means that it is possible to use Groovy
Eclipse despite the fact that it has formatter regressions (see
https://github.com/groovy/groovy-eclipse/issues/142).

Fixes gh-4136

CONTRIBUTING.adoc

@@ -129,17 +129,19 @@ eclipse. If you don't already have m2eclipse installed it is available from the
 marketplace".
 
 Spring Boot includes project specific source formatting settings, in order to have these
-work with m2eclipse, we provide an additional eclipse plugin that you can install:
-
-* Download `org.eclipse.m2e.maveneclipse.site.zip` from
-  https://github.com/philwebb/m2eclipse-maveneclipse/releases.
-* Select `Install new software` from the `help` menu
-* Click `Add...` to add a new repository
-* Click the `Archive...` button
-* Select the `org.eclipse.m2e.maveneclipse.site.zip` that you previously downloaded
+work with m2eclipse, we provide additional Eclipse plugins that you can install:
+
+===== Install the m2eclipse-maveneclipse plugin
+* Select "`Help`" -> "`Install New Software`".
+* Add `https://dl.bintray.com/philwebb/m2eclipse-maveneclipse` as a site.
 * Install "Maven Integration for the maven-eclipse-plugin"
 
-NOTE: This plugin is optional. Projects can be imported without the plugin, your code
+===== Install the Spring Formatter plugin
+* Select "`Help`" -> "`Install New Software`".
+* Add `https://dl.bintray.com/philwebb/spring-eclipse-code-formatter/` as a site.
+* Install "Spring Code Formatter"
+
+NOTE: These plugins are optional. Projects can be imported without the plugins, your code
 changes just won't be automatically formatted.
 
 With the requisite eclipse plugins installed you can select

eclipse/org.eclipse.jdt.core.prefs

@@ -388,3 +388,4 @@ org.eclipse.jdt.core.formatter.use_tabs_only_for_leading_indentations=false
 org.eclipse.jdt.core.formatter.wrap_before_binary_operator=true
 org.eclipse.jdt.core.formatter.wrap_before_or_operator_multicatch=true
 org.eclipse.jdt.core.formatter.wrap_outer_expressions_when_nested=true
+org.eclipse.jdt.core.javaFormatter=org.springframework.ide.eclipse.jdt.formatter.javaformatter