add a list of zones and the option to delete them (Billing)

+ rename list, as it collides with an imported method from Sipwise::Base
fix TT warning

it complained argument "" isnt numerical
fix some URIs and fix redirection on fees_create

Closes: sipwise-0003085
outsource modal, introduce peaktime page

modal uses a separate template file now
the weekdays edit modal is WIP
billing weekdays: option to add/delete time ranges
show peaktime dates as datatables table
fix syntax (indirect call)

fix syntax so that indirect cannot complain
now we can use correct scope for Sipwise::Base
implement create/edit/delete of billing_peaktime_special
Make Preferences a button

Closes: sipwise-0003083
prevent deletion of billing_profiles

Billing-Profiles MUST NOT be deleted
Fixes: sipwise-0003127
provide CSV upload of billing_fees

using Text::CSV_XS
add tests for billing controller

and make weekdays generic