Add arch/encoding metadata to DB + Fetch Arch Linux x86_64

The encoding metadata will be very useful in finding badly decoded man
pages. The package 'arch' is necessary to properly identify which
package was used, which is not obvious now that I'm going to switch more
systems to the (more common) x86_64 arch.

indexer/src/main.rs

@@ -42,6 +42,7 @@ fn main() {
             (@arg pkg: --pkg +required +takes_value "Package name")
             (@arg ver: --ver +required +takes_value "Package version")
             (@arg date: --date +required +takes_value "Package release date")
+            (@arg arch: --arch +takes_value "Architecture")
             (@arg FILE: +required "Package file")
         )
         (@subcommand arch =>
@@ -81,6 +82,7 @@ fn main() {
             pkg: matches.value_of("pkg").unwrap(),
             ver: matches.value_of("ver").unwrap(),
             date: matches.value_of("date").unwrap(),
+            arch: matches.value_of("arch"),
             file: open::Path{ path: matches.value_of("FILE").unwrap(), cache: false, canbelocal: true},
         });
     }