slack-integration: added number of commits inside the message.

rhodecode/integrations/types/slack.py

@@ -263,7 +263,7 b' class SlackIntegrationType(IntegrationTy'
 
         repo_push_template = Template(textwrap.dedent(r'''
         %for branch, branch_commits in branches_commits.items():
-        branch: <${branch_commits['branch']['url']}|${branch_commits['branch']['name']}>
+        ${len(branch_commits['commits'])} ${'commit' if len(branch_commits['commits']) == 1 else 'commits'} on branch: <${branch_commits['branch']['url']}|${branch_commits['branch']['name']}>
         %for commit in branch_commits['commits']:
         `<${commit['url']}|${commit['short_id']}>` - ${commit['message_html_title']|html_to_slack_links}
         %endfor