Enable method returns text encoding instead of json

https://github.com/aristanetworks/goeapi/blob/7944bcedaf212bb60e5f9baaf471469f49113f47/client.go#L305

Although the documentation and variable name imply json output, the output is coded to text. Could we either expose `runCommands` as a public method or change the default behavior to be json encoding?

Start at client.go around line 305 and inspect the method documented as returning JSON, including the runCommands path and its callers. Determine whether the intended resolution is exposing runCommands or changing the default encoding, then verify that the documented behavior, variable name, and returned output agree.

Written by the indexing model from the issue text.