Handle 404 and 500 errors

Use custom handler for 404 and 500 errors
Redirect to #404 and #500 so that pages are rendered correctly,
and backbone can display appropriate error templates
Merge branch 'master' into issue#345_404
Merge branch 'issue#345_404' of git://github.com/sujeetsr/rockstor-core into sujeetsr-issue#345_404
Modified template and html files
Merge branch 'issue#345_404' of git://github.com/sujeetsr/rockstor-core into sujeetsr-issue#345_404
Add 404 and 500 views to views/__init__
Merge branch 'issue#345_404' of git://github.com/sujeetsr/rockstor-core into sujeetsr-issue#345_404
Added 404 and 500 views
Merge branch 'issue#345_404' of git://github.com/sujeetsr/rockstor-core into sujeetsr-issue#345_404
Handle 404 and 500 errors

Add global error handler for ajax error
Add global error message template
Remove cutom 404 adn 500 django handler view
Modify 404.html and 500.html
Merge branch 'master' into issue#345_404
Fixes #358

Validate share name during post and standardize the regex.
Validate pool name during post and standardize the regex.
update smb.conf template for 2.0
Modifications to handle ajax errors globally
bugfix: browseable typo guest ok
update smb.conf to allow guest login
Add avahi conf file for Samba
brand smb.conf with rockstor
update buildout for smb/avahi stuff