Use overflow in webshell paste to allow big content

Ticket:	#4886
Allow an arbitrary size for webshell paste

Previously it was limited to ~1000 chars.

Ticket:	#4886
Replace using ldap to resolve names to using winbind with ad backend
Don't forget about pam!
Add current draft of FreeNAS User Guide, suitable for nightly HTML build.
Add images for User Guide to images directory.
Add README for building HTML version of User Guide.
Use the correct confset function
Remove trailing slash

Ticket: #4669