Changeable testrail credential

Change-Id: I68732c842a933922e1ed03920d9fb3cafaeed459
diff --git a/src/com/mirantis/tcp_qa/Common.groovy b/src/com/mirantis/tcp_qa/Common.groovy
index 817f893..37328d6 100644
--- a/src/com/mirantis/tcp_qa/Common.groovy
+++ b/src/com/mirantis/tcp_qa/Common.groovy
@@ -172,9 +172,11 @@
     report ${reporterOptions.join(' ')} ${junitXml}
   """
 
+  def testrail_cred_id = params.TESTRAIL_CRED ?: 'testrail'
+
   withCredentials([
              [$class          : 'UsernamePasswordMultiBinding',
-             credentialsId   : 'testrail',
+             credentialsId   : testrail_cred_id,
              passwordVariable: 'TESTRAIL_PASSWORD',
              usernameVariable: 'TESTRAIL_USER']
   ]) {