fixed config creation
demo_user
Saner logging

- Log files are now written in log-dir explicitly set from the
  command-line
- Also log messages have timestamps now
fixing testcases so that they can be run from any level
Converted the demodb into a class
Logging and fixed range

Added logging to demo_user. Also fixed a bug in demo_user to include
last day in the sequence.
Added facility to show work for last n weeks/days
Bugfix: file_path and intro

file_to_be_created should not be set just because file_path is missing.
On the other hand, since we update the config file every time we
instantiate config, we have to write the intro every time if we want it
to be part of the config permanently.