Update to match tagging guidelines:
Update to match tagging guidelines:

`beta` tag will stay up to date (stability wise) with master/`latest`; but when developing on a branch, `beta` tag is included for convenience. (rather than changing image to `test1` or `test2`)

the most recent version number (of versioned data services) will be unversioned `latest` and `beta` following beta/branch tag naming, all other versions will have tags `$VERSION` and/or `$VERSION-[beta|$BRANCHNAME]`

nanobox-io/nanobox-docker-memcached,pagodabox/nanobox-docker-memcached,pagodabox/nanobox-docker-memcached,pagodabox/nanobox-docker-memcached