Update cflager to lagerflags
Update cflager to lagerflags

- cflager is deprecated in favor of
  code.cloudfoundry.org/lager/lagerflags

[#172222480](https://www.pivotaltracker.com/story/show/172222480)

cloudfoundry-incubator/galera-healthcheck,cloudfoundry-incubator/galera-healthcheck