__repr__ for paramStore needs improvements

[galwiner]

The current paramstor __repr__ method is not sufficiently descriptive.

[galwiner]

@liorella-qm can you please describe the data you would like to see in this method?
the entire content of the param store?

[liorella-qm]

maybe I can add a pull request with ideas once I start working with it?

[galwiner]

@liorella-qm is this still a problem?