- Normalize jailname.  "example.com" is converted to "example_com".
- Fix a bug that some $jail_{jname}_foo variables did not work.
- Fix a bug which prevented $jail_devfs_ruleset from working[1].
- Move $jail_parameters to the last of the configuraiton lines[1].

Reported by:	Jase Thew[1]
Approved by:	re (glebius)