try to resolve travis/java6 build issue; seems to stem from Felix/bundle plugin requiring Java 7 or later
diff --git a/pom.xml b/pom.xml
index 7c92697..c8c96ad 100644
--- a/pom.xml
+++ b/pom.xml
@@ -27,6 +27,12 @@
<javac.src.version>1.6</javac.src.version>
<javac.target.version>1.6</javac.target.version>
+ <!-- 04-May-2016, tatu: Bundle-plugin 3.x seems to require Java 7, so to
+ build for Java 6 need to downgrade here to last working 2.x version
+ (2.5.4 had some issues wrt shading)
+ -->
+ <version.plugin.bundle>2.5.3</version.plugin.bundle>
+
<osgi.export>com.fasterxml.jackson.core;version=${project.version},
com.fasterxml.jackson.core.*;version=${project.version}
</osgi.export>