fixing issue with instances, should return one

[vsoch]

This PR will fix the Client.instances() command so that if the user provides a name, a single instance is returned instead of a list. This will close #83

[vsoch]

@al3x609 if you might kindly test the PR here - we want to make sure:

• when more than one instance is running, when you do Client.instances("myinstance") (providing a particular name) it returns an instance object (and not a list).
• the issues with version 2.* checking are fixed here too :)

[vsoch]

ok fixed.

[vsoch]

@al3x609 ready for merge?

[vsoch]

https://pypi.org/project/spython/0.0.51/

[al3x609]

👍 :)