Enable SSH automatically when the site uses SSH

Merged from 66dfd17 of branch pref_test of pcman-firefox
Use username 'bbs' automatically for
ptt.cc:22
ptt2.cc:22
ptt3.cc:22
Prompt for UserPass similarly to putty for other sites

Support preliminary SSH connection

The SSH library is paramikojs written by Mime Cuvalo,
merged from 62b8310 of branch pref_test of pcman-firefox
When telnet to ptt.cc with port 22,
the SSH function is enabled automatically.

Fix minor bugs

Fix bugs found in pcman.js