Support real domain aliases

Fixes #11

ViMbAdmin supports catch-all addresses, but doesn't support real domain aliases (rule "@example.com --> @example.net" redirects foo@example.com to foo@example.net). Pretty strange, because this can be achieved by simply allowing "@example.com" as goto of aliases. Postfix does the rest.

Fixes some popover styling issues, too.
Merge pull request #101 from PhrozenByte/feature/supportDomainAliases

Support real domain aliases