Added support for .bash_profile, .bash_login and .profile

[sfreytag]

This pull request supplies code to extend some of the work done to support Mac OS X users.

Mac OS X will attempt to read the PATH information required by this plugin from these three files, in order: .bash_profile -> .bash_login -> .profile

I have extended the ConstructCommand function to try to find one of these files, in that order, or issue a warning and stop if it cannot find any of them. Hopefully that is useful.

My branch also contains a merge of mattyork's p4v integration, simply because I quite wanted that functionality too. This may, or may not, be helpful...

Thanks for writing this plugin! I hope to use it quite a lot, and contribute some more extensions. Next on my list is to link Perfoce Checkout with a window.show_quick_panel(pending change lists here) so you can checkout a file to a non-default CL.

cheers,

Simon