Set group name to -n parameter (or exe name)

- As discussed in #469

projects/SelfTest/Baselines/junit.sw.approved.txt

@@ -1,5 +1,5 @@
 <testsuites>
-  <testsuite name="all tests" errors="12" failures="88" tests="804" hostname="tbd" time="{duration}" timestamp="tbd">
+  <testsuite name="CatchSelfTest" errors="12" failures="88" tests="804" hostname="tbd" time="{duration}" timestamp="tbd">
     <testcase classname="global" name="toString(enum)" time="{duration}"/>
     <testcase classname="global" name="toString(enum w/operator&lt;&lt;)" time="{duration}"/>
     <testcase classname="global" name="toString(enum class)" time="{duration}"/>

projects/SelfTest/Baselines/xml.sw.approved.txt

@@ -1,5 +1,5 @@
 <Catch name="CatchSelfTest">
-  <Group name="all tests">
+  <Group name="CatchSelfTest">
     <TestCase name="toString(enum)">
       <Expression success="true" type="CHECK" filename="projects/SelfTest/EnumToString.cpp" >
         <Original>