Adding WWW::CheckSite

WWW::CheckSite it's not anymore on cpan, but it's on backpan
Here, the dependency should read:

```bash
echo \>=virtual/perl-ExtUtils-MakeMaker-6.300.0
```

Because there's no "Old style" virtuals in ::gentoo for MakeMaker around `6.30`

```
[I] virtual/perl-ExtUtils-MakeMaker
     Available versions:  **6.630.200_rc[1] 6.640.0 (~)6.660.0 (~)6.820.0 [M](~)6.980.0
     Installed versions:  6.820.0(17:42:26 03/31/14)
```

To get "new" versions, install `dev-perl/Gentoo-PerlMod-Version` and do:

```bash
gentoo-perlmod-version.pl 6.30
```

Its unfortunately a really complicated issue : https://wiki.gentoo.org/wiki/Project:Perl/perl-herd#Version_numbers_in_Gentoo_perl_ebuilds

The TL;DR version being: 

1. Upstream have two version schemes to choose from
2. One of those schemes is completely incompatible with gentoo and gentoo will interpret it backwards
3. Upstream switch between schemes regularly
4. Upstream are known to break things in versioning if we even pretend their versions are sane.

==> We force normalization of CPAN versions in all cases to a scheme Gentoo understands.