Specify checkstyle suppression in config file.

Backported from OVX
 https://review.gerrithub.io/3549
-- description by Marc --
  The idea is to have maven and eclipse share the same checkstyle config.
  We still setup the suppression, but inside the sun_checks.xml file.
  Here we’re using a variable that is standard in Eclipse, but unknown by Maven.
  The propertiesLocation allows us to define the variable in the scope of Maven.

  See here for more info: http://rolf-engelhard.de/2011/04/using-the-same-suppression-filter-for-checkstyle-in-eclipse-and-maven/
----

Change-Id: I4d1083002db94556d31febdca9fc6d19745a0ce8
diff --git a/conf/checkstyle/checkstyle_maven.properties b/conf/checkstyle/checkstyle_maven.properties
new file mode 100644
index 0000000..4677e08
--- /dev/null
+++ b/conf/checkstyle/checkstyle_maven.properties
@@ -0,0 +1,2 @@
+# See: http://rolf-engelhard.de/2011/04/using-the-same-suppression-filter-for-checkstyle-in-eclipse-and-maven/
+config_loc=conf/checkstyle