correctly use configuration file if provided on the CLI

Hello,

this pull request fix the following bug:
- if configfile is specified on the CLI, the script still test the presence of ./report.config instead of the specified file
- if configfile is specified on the CLI and does not exist, the default config file is written as ./report.config file instead of the specified file
- if --defaultconfig is used in conjunction with -r configfile, the default config file is written as ./report.config file instead of the specified file

Also, it would facilitate contribution if your code was respecting PEP8 specification.

Regards,
John