Don't update apt sources pointing to mirrors.

Here we stop babushka from writing a new apt sources file if apt is already pointing to a country mirror. Babushka will now also accept trailing slashes on deb sources.

Some fairly detailed descriptions here: 56808995db7d89ba003c9d0781bb72203f7bdd38 and here: 9df2226291d8de9aa689b38f3008d2b2bd8e64c2

Also added "tags" (ctags) as a file to be ignored by git.