1.6 fix

Added 1.6 compatibility for all jars
Also, removed mavenUrl since it is ineffective in my setup.  repo1.maven.org rarely works well from China.  So in order for me to build I just had to manually override the mavenCentral() with my own maven config.  the if(hasProperty('mavenUrl')) just doesn't work.  Instead of adding cruft to the build file I think its better to just take it out for now.  I did some research and there are some plugins that do what we want (add support for a local.gradle) but we can discuss that later if there is more demand for setting up local nexus repos.  For now I can just temporarily modify my build.gradle to work in our office.