Remove dependency on suite_id and use test plan

[dsayling]

The suite_id is included in the individual case when retrieved from testrail.

Often we are executing multiple testcases that span multiple suites at once, so specifying a single suite in the config file doesn't make much sense.

I think ideally a test plan should be created on every behave run that adds all the suites for every testcase executed. Then the results are uploaded for all the testcases run from the suite.