[FTO-DRAFT] Add option to set a name for set of generated names.

[M-Zuber]

Currently each instance of Tyche will keep track of the names generated so as not to repeat them.
In order to enable the inclusion of Tyche in client apps that may be always using the same instance we need to be able to pass in an (optional) argument that gives a name to the set.
The name will be prepended to the file that tracks previously generated names.
Steps:

• Add flag in code - it gets passed to Generator object
  • Set default as none or default?
  • add a test or two
• Add documention in readme
• Add docs in docs folder