changes necessary for cloudera cdh 5

Thanks for the effort on RImpala. I have been using it fine with CDH 4.x.x. But recently we switched to CDH 5.1.0 and current RImpala is not compatible. I found that the problem is from dependency. In this pull request, I modified pom.xml and added the zip file containing latest jar files. 

Please test it and let me know if you have any concern.