Enable parallel mode for the OptimizationSolver.

[GaboFGuerra]

Issue Number: #170

Objective of pull request: As a user of the OptimizationSolver I want to run the CPU Optimization solver with many parallel configurations running simultaneously to get higher solution probability and a lower time to solution.

Pull request checklist

Your PR fulfills the following requirements:

• Issue created that explains the change and why it's needed
• Tests are part of the PR (for bug fixes / features)
• Docs reviewed and added / updated if needed (for bug fixes / features)
• PR conforms to Coding Conventions
• PR applys BSD 3-clause or LGPL2.1+ Licenses to all code files
• Lint (pyb) passes locally
• Build tests (pyb -E unit) or (python -m unittest) passes locally

Pull request type

Please check your PR type:

• Feature

What is the current behavior?

• OptimizationSolver runs a single instance per problem and hyperparameter set.

What is the new behavior?

• Many replicas of the SNN defined by the solver process are created according to the number of hyperparameter sets passed by the user.

Does this introduce a breaking change?

• No