Fix testrail reporter

1. Pin 'testrail' PyPI package to version 0.3.8 to avoid such error:

    File "/home/jenkins/fuel-devops30/local/lib/python2.7/site-packages/testrail/helper.py", line 83, in <dictcomp>
      return dict({match[1]: match[0] for match in matches if match})
  TypeError: '_sre.SRE_Match' object has no attribute '__getitem__'

2. Fix empty plan errors like:

    File "tcp-qa/tcp_tests/report.py", line 91, in get_runs
      for e in plan.entries:
  AttributeError: 'NoneType' object has no attribute 'entries'

Change-Id: I670c5bd5789287c7d7fa612e7944d954e4b3808b
diff --git a/tcp_tests/requirements.txt b/tcp_tests/requirements.txt
index d419b33..f508205 100644
--- a/tcp_tests/requirements.txt
+++ b/tcp_tests/requirements.txt
@@ -13,7 +13,7 @@
 junit-xml
 jinja2>=2.1
 jira
-testrail
+testrail<=0.3.8
 functools32
 python-k8sclient==0.4.0
 salt-pepper<=0.5.3