enable property override of nsync.cc.base_url
enable property override of nsync.cc.base_url

[#144562223]

Signed-off-by: James Myers <2a4b62c1f90dfaec9bbec6fa717dcd6575faa328@gmail.com>

cloudfoundry-incubator/diego-release,cloudfoundry-incubator/diego-release,cloudfoundry-incubator/diego-release,cloudfoundry-incubator/diego-release