dfs collectors should have same permissions as other collectors

Recently, when setting up tcollectors on boxes which are both dfs data nodes, and hbase regionservers, I was surprised to notice that they were emitting hbase metrics, but not datanode metrics. After some poking around I realized that hadoop_datanode.py and hadoop_namenode.py had different permissions than all the other collectors/0/ scripts (namely they were not set as executable by anyone), and fixing this permissions issue allowed tcollector.py to start sending datanode metrics.