Remove the dependency on configobj and have default values for all
configuration settings. User settings are defined in a Python module
pointed to by the MUTALYZER_SETTINGS environment variable.

We also clean up many configuration settings and remove some that
are no longer used.

We no longer look for /etc/mutalyzer/config and ~/.config/mutalyzer/config
since it is too low level and inflexible. The user should now specify the
location of the configuration file in the MUTALYZER_SETTINGS environment
variable (or the file mutalyzer.conf in the current directory is tried).

We should leave process control to others, for example supervisord which
can automatically restart crashed processes.

Do not try to implement a full UNIX daemon suitable for init.d with the
batch daemon, but rather keep it simple and depend on something like
supervisord to implement process control.

We now also correctly handle SIGINT (Ctrl+C) and SIGTERM signals.

This changes the output format of the JSON webservice. Results are no longer
wrapped (twice) in an object. For example, the request

    /checkSyntax?variant=AB026906.1:c.274del

used to return

    {"checkSyntaxResponse": {"checkSyntaxResult":
      {"valid": true, "messages": {"SoapMessage": []}}}}

and now returns

    {"valid": true, "messages": []}

We also use "soft" input validation.

See http://stackoverflow.com/a/12297929

This removes the need for the top-level package_root function. On the
way we also remove the top-level is_test function that was obsolete.

This is more in line with common practice. Furthermore, the web.py
built-in HTTP server only looks there (hard-coded unfortunately), so
this is the only way to easily run Mutalyzer without a separate
webserver.