Add get_result method to st2client

[skiedude]

In order to check the results of a given execution, this endpoint is invaluable. The get_output method can sometimes return the information, but not always.

This method will be pulling information from the /api/v1/executions/{id}/result endpoint and returns a json response

[CLAassistant]

All committers have signed the CLA.

[guzzijones]

please update the commit or sign the CLA for the Jacob Zufelt commit

[skiedude]

@guzzijones sorry about that, fixed

[guzzijones]

looks like the lint check failed.

[skiedude]

Seems to be unrelated to my change

1. st2-auth-ldap 3.9.dev0 from git+https://github.com/StackStorm/st2-auth-ldap.git@master
    Expected sha256 hash of 29c6ff480b24e4bc316ed69eac5503c71f4700ed17649ae5c5ca8cd745e5852f when downloading st2-auth-ldap but hashed to 1b62240f8004316de753c3e2e20e629d0afb3337ea9a549f9022b4a7ba8c0499.

[skiedude]

Same lint check is failing, not sure how my code change could have done this

1. st2-auth-ldap 3.9.dev0 from git+https://github.com/StackStorm/st2-auth-ldap.git@master
    Expected sha256 hash of 29c6ff480b24e4bc316ed69eac5503c71f4700ed17649ae5c5ca8cd745e5852f when downloading st2-auth-ldap but hashed to 1b62240f8004316de753c3e2e20e629d0afb3337ea9a549f9022b4a7ba8c0499.
    ```

[skiedude]

@guzzijones is there more I need to do, in order to get a 2nd approver?

[skiedude]

@cognifloyd can you do a 2nd review?

[skiedude]

Is the milestone something I need to set? @cognifloyd