FIO : Added performance test for Linux on Azure

This test performs FIO disk test on resource disk - /mnt or /mnt/resource (depending on linux distribution)
Following configurations are controlled from XML file -
1.io size
2.queue depth
3.test file size
4.test run time
Each test run will create different fio output file and will be saved in default log directory.
help is given wrong here. I'll fix it in next commit.