Clean-up params

[andrewvc]

We currently have suite-params (argument), params (variable available in user scripts), and RunParams (internal variable, params + env) in various places in our code. This gets confusing!

We can and should simplify this all pre-GA to:

• params is the only kind of params, with --suite-params and -s deprecated in favor of -p and --params
• rename all internal variables to params
• Get rid of the -e and --environment flag, in favor of NODE_ENV
• Keep `params as the variable in use in scripts.

While this is a breaking change it is likely that very few people are using these options.