Remove uniqueVolumeIds flag
Remove uniqueVolumeIds flag

- This is hard coded in driver
[#170986312](https://www.pivotaltracker.com/story/show/170986312)
Authored-by: Lisa Cho <53c7312eb9f02149a2ed58fc14d78d4142caa3c0@pivotal.io>

cloudfoundry-incubator/nfs-volume-release,cloudfoundry-incubator/nfs-volume-release,cloudfoundry-incubator/nfs-volume-release