* Nomad: updating max token length to 256
* Initial support for supporting custom max token name length for Nomad
* simplify/correct tests
* document nomad max_token_name_length
* removed support for max token length env var. Rename field for clarity
* cleanups after removing env var support
* move RandomWithPrefix to testhelpers
* fix spelling
* Remove default 256 value. Use zero as a sentinel value and ignore it
* update docs
Jeff Mitchell