minor: Revert "Issue #3323: use Orekit fork to pass CI for this issue"

This reverts commit 7a8b92371b.

wercker.yml

@@ -22,7 +22,8 @@ build:
         -Dcheckstyle.ant.skip=true -Dcheckstyle.skip=true -Dxml.skip=true
         && CS_POM_VERSION=$(mvn -q -Dexec.executable='echo' -Dexec.args='${project.version}' --non-recursive org.codehaus.mojo:exec-maven-plugin:1.3.1:exec)
         && echo CS_version: ${CS_POM_VERSION}
-        && git clone https://github.com/checkstyle/Orekit.git && cd Orekit
+        && git clone https://github.com/CS-SI/Orekit.git && cd Orekit
+        && git checkout 942785a5c79b5470baec3d41cab18f3adc78280e
         && mvn compile checkstyle:check -Dorekit.checkstyle.version=${CS_POM_VERSION}
 
   # NoErrorTest - XWiki (oraclejdk8)