Update Plexus components so Git-related tests will pass.

Author: Roger Hu

src/main/resources/META-INF/plexus/components.xml

@@ -37,5 +37,12 @@ under the License.
       <implementation>org.apache.maven.scm.provider.svn.svnjava.SvnJavaScmProvider</implementation>
       <!-- <implementation>org.apache.maven.scm.provider.svn.svnexe.SvnExeScmProvider</implementation> -->
     </component>
+
+    <component>
+      <role>org.apache.maven.scm.provider.ScmProvider</role>
+      <role-hint>git</role-hint>
+      <implementation>org.apache.maven.scm.provider.git.gitexe.GitExeScmProvider</implementation>
+    </component>
+
   </components>
 </component-set>