Added settings to customize notification and translations to important parts of the message.
[FIX] Security fixes and simplified customization
Field `show_followers_partner_format` formatted with %(param)s
Removed CSS customizations
[FIX] README options
[FIX] Index.html configure
[FIX] Several changes
- Removed unnecesary properties on res_config_settings
- Markup safe on partner_format
- Use email_domain_extract instead own one
As commented in https://github.com/OCA/social/pull/788 the PR should be merged manually but we should update the version of the module as a minor update
cc @ValentinVinagre @eLBati @MiquelRForgeFlow @HaraldPanten
