* add kill user job alert template
* add troubleshooting link in general email template
* allow customized templates
* redefine actions schema in customized-receivers to facilitate parameters passing
- move requirement check before configuration setting;
- move quick-start-config folder setting to quick-start-services.sh;
- fix installation document branch checkout issue; change suggested version to v1.3.y;
- refine uninstallation doc
- fix git clone issue: clone to an existing folder may raise error, so the code pai/kubespray may be unsuccessfully cloned.