Add support for authentication other than VistA based

VistA based authentication has been removed.

Simple username password based authentication has been added.

Tasks:

• Specify Usernames/password/permissions via STDIN
• Specify Usernames/password/permissions via environment variable ydbgui_users
• Login
• Provide tokens
• Remove Basic Authentication old username/password implementation
• Determine authorization (RO/RW) at runtime
• Enable token timeout code
• Token clean-up by time
• Enable token clean-up by time code
• Timeout enforcement
• Logout
• Disable Timeout and Logout until we generate random tokens
• MR
• Share token data between parent and child processes
• Dynamically generate tokens at runtime (currently static)
• Enable Timeout and Logout
• Decide what to do about multiple servers running if we have a single database.
• Documentation
• MR
• File-based usernames/passwords with password encryption: implementation to be decided
• PAM authentication (RO- cannot do RW as we don't have that information right now)
• Documentation
• MR