Added support for hashed directories

[xme]

If you use CertStreamMonitor to track many websites like me, the number of JSON files created in the alerts directory may quickly become unmanageable.
I added support for hashed directories to create sub-directories based on the server current time.
You can define an alerts directory in the config like:

./alerts/%%Y/%%m/%%d

And sub-directories will be created to store alerts at each new scanhost.py execution.

What do you think about an option to create hashed directories based on the FQDN?
Ex:
./alerts/be/rootshell/blog/

[xme]

Small bug fix (indentation)

[cbrocas]

Hi Xavier!
Xavier, thank you very much for this useful PR!

We see two modifications that can be useful before merging :

• conf/example.conf: do not modify the Alerts_dir parameter value in the configuration file (ie not adding /%%Y/%%m/%%d)
• def generate_alert_dir(path): append (an not replace so) /%Y/%m/%d values to the directory name generated by this new function

The main benefits would be :

• we keep your feature (adding timestamp hashed alerts sub-directories)
• the feature is strictly compatible with current installations and implies no modification at all of the configuration file for existing users.
• it requires no migration code to handle previous version of the Alerts_dir keyword (ie without any reference to time/date)

Agree with this proposal ?

[xme]

Agree but this means that the user won't be able to select the directory hierarchy fitting best for him.
Ex:
/YYYY/mm
/YYYY/mm/dd
/HH/MM

My change is compatible with existing config files because nothing is replaced if no "%" is found :)

I've almost implemented the other suggestion to make sub-dirs based on the FQDN... PR on its way :)

[cbrocas]

Retro compatibility : and ... you are right ! OK for me.