Help command fixes

I found few issues with help command. When you try to get help about a flag it was throwing a pattern compile exception. Then I fixed it with a simple Pattern.quote. Then the same command wouldn't help at all because I was trying to get help about a flag and not a group, so it was not showing any help, it was showing a red message saying that the server has no flags, than I changed to include the flag in the list if the flag name was typed as argument because a flag description is better than nothing.

The last commit fixes the help command usage description, some sub-commands were wrong, for example /flag view would do nothing be cause the correct command is /flag viewtrust