Handle GitLab Dash URLs for certain Web Tests

Closes #216 (closed)

Some GitLab Web Project URLs now sometimes have dashes in their path. This is dependent on the version of GitLab and when it is the case GitLab will redirect for some.

For our comparison pipeline this puts us in an awkward spot with GPT. k6 can handle a redirect but it also counts it separately as a request, leading to inflated numbers.

MR brings in a solution that intelligently handles the URL's potentially being different depending on GitLab version for the select test endpoints that are affected by it.

Example results (ignore time failures, key thing is req status):

* Environment:                Staging
* Environment Version:        12.9.0-pre `a316b39d106`
* Option:                     20s_2rps
* Date:                       2020-03-25
* Run Time:                   2m 35.4s (Start: 16:45:59 UTC, End: 16:48:35 UTC)
* GPT Version:                v1.2.4

➤ Overall Results Score: 92.86%

NAME                                  | RPS | RPS RESULT       | TTFB AVG  | TTFB P90            | REQ STATUS     | RESULT
--------------------------------------|-----|------------------|-----------|---------------------|----------------|----------------
web_project_branches                  | 1/s | 1.0/s (>0.80/s)  | 1017.83ms | 1303.24ms (<3500ms) | 100.00% (>95%) | Passed
web_project_issue                     | 1/s | 1.05/s (>0.80/s) | 538.15ms  | 1222.36ms (<3500ms) | 100.00% (>95%) | Passed
web_project_issues                    | 1/s | 1.05/s (>0.80/s) | 540.78ms  | 734.48ms (<2500ms)  | 100.00% (>95%) | Passed
web_project_merge_request_changes     | 1/s | 0.65/s (>0.80/s) | 1797.59ms | 2847.24ms (<6000ms) | 100.00% (>95%) | Passed
web_project_merge_request_commits     | 1/s | 0.95/s (>0.80/s) | 776.15ms  | 1221.23ms (<3000ms) | 100.00% (>95%) | Passed
web_project_merge_request_discussions | 1/s | 0.7/s (>0.80/s)  | 1384.60ms | 3502.77ms (<6000ms) | 100.00% (>95%) | Passed
web_project_merge_requests            | 1/s | 1.1/s (>0.80/s)  | 563.73ms  | 812.46ms (<2500ms)  | 100.00% (>95%) | Passed