New config keys in [mailer] section:
 - CERT_FILE: path to a certificate file.
 - KEY_FILE: path to a key file.

- routers: use new binding convention to simplify code
- templates: able to set HTTP port number in install page

The SendMail function is rewritten and has the following new functionality:
 - It is optional to skip verification of keys. The config option SKIP_VERIFY is added
 - If the port is 465, or ending on 465, the TLS(/SSL) connection is started first.

Conflicts:
	modules/setting/setting.go

Conflicts:
	templates/repo/release/list.tmpl
	templates/user/dashboard/dashboard.tmpl

Conflicts:
	routers/repo/setting.go