feat - Add pause feature

[egallyamov]

First of all, that's really helpful to have such an automated backup tool.
Installation is straightforward for someone who knows how to use linux.

Now some points of possible improvements:

1. Include the exclude_files list or document it if it is already included
2. Add some more functionality to the button:
   • Frequency of backups
   • Pause restic (pause backups when not on EPFL network)

[sbancal]

Thanks for your feedback egallyamov,

1. As discussed in your pull request, the exclude_files feature has been integrated into latest release so this is now complete.

2. Regarding the frequency of backups, it can be adjusted by the end user by editing the ~/.enacrestic/state.json file and change the backup_every_n_minutes value. This has to be done while ENACrestic isn't running. Then run it again and the new setting will be taken into account.

3. Pause ENACrestic is an important and really useful feature request ... that will need some more time to be implemented. I'll have to check what will be the behavior if the user requests a pause while a backup or a forget is being running so that it won't break / corrupt the repo. By the way, if you're outside EPFL, without VPN, backup attempts will just finish into a Network Timeout.

I'll keep this issue open to let you know when something has moved on point 3.

[sbancal]

Pause backup would technically mean to kill restic process. Un-pause means launch it again.

Kill restic process might be usefull when stopping ENACrestic app.