Fix #138: Correct misspelled ENVVAR used to transmit config group

Changes

@@ -5,6 +5,7 @@ Revision history for Perl module TestRail::API
     - Fix issue where Test plans were not recorded in the raw output of a case.
     - Add ability to specify a custom status for failures which emit no test plan
     - Change tests which emit a plan but no assertions into failures.
+    - Fix issue where configuration groups in the testrailrc were ignored
 
 0.040 2017-05-24 TEODESIAN
     - Fix performance issue in TestRail::Utils::Find::FindTests

lib/App/Prove/Plugin/TestRail.pm

@@ -123,7 +123,7 @@ sub load {
     $ENV{'TESTRAIL_SECTIONS'}  = $params->{sections};
     $ENV{'TESTRAIL_AUTOCLOSE'} = $params->{autoclose};
     $ENV{'TESTRAIL_ENCODING'}  = $params->{encoding};
-    $ENV{'TESTRIAL_CGROUP'}    = $params->{'configuration_group'};
+    $ENV{'TESTRAIL_CGROUP'}    = $params->{'configuration_group'};
     $ENV{'TESTRAIL_TBAD'}      = $params->{'test_bad_status'};
     return $class;
 }