Be nice to people named 'pg'

Hola,

I noticed the `page_handler`'s regular expression to skip `/pg/` actually discriminates any part of an URL's path. E.g., it would break the link to someone's profile called __pg__.

This commit fixes that. It also comes with space fixes, as my Emacs is configured to follow Elgg Coding Standard. I can do two commits if necessary, but the simplicity of the change does not warrant it IMO.