limit cli maxpeers

[ixje]

What current issue(s) does this address, or what feature is it adding? the sc config maxpeers/minpeers command already has a 10 peers max limit imposed. The cli arguments did not.

How did you solve this problem? add argument choices limit

How did you make sure your solution works? manual testing. now gives the following error if a wrong argument is given

np-api-server: error: argument --maxpeers: invalid choice: 12 (choose from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10)

Are there any special changes in the code that we should be aware of?

Please check the following, if applicable:

• [ ] Did you add any tests?
• [X] Did you run make lint?
• [ ] Did you run make test?
• [X] Are you making a PR to a feature branch or development rather than master?
• [ ] Did you add an entry to CHANGELOG.rst? (if not, please do)

[coveralls]

Coverage remained the same at 85.263% when pulling 9aa166eaeaa9ac1486f797fe9072005ac46b1b15 on ixje:fix-maxpeers into 338189c529d350ae69288decad893a68ce7b494f on CityOfZion:development.