Downgrade to Buildship 3.0.0

See gh-117

Author: philwebb

spring-javaformat-eclipse/io.spring.javaformat.eclipse/META-INF/MANIFEST.MF

@@ -16,7 +16,7 @@ Require-Bundle: org.eclipse.ui,
  org.eclipse.m2e.jdt;resolution:=optional,
  org.eclipse.m2e.core;resolution:=optional,
  org.eclipse.m2e.maven.runtime;resolution:=optional,
- org.eclipse.buildship.core;bundle-version="3.1.0";resolution:=optional,
+ org.eclipse.buildship.core;bundle-version="3.0.0";resolution:=optional,
  net.sf.eclipsecs.core;bundle-version="8.18.0";resolution:=optional
 Bundle-ClassPath: .,
  lib/spring-javaformat-formatter-eclipse.jar,