fixing use of uninitialized value in concatenation and enhancing output in App/Cpan.pm

Fixing Use of uninitialized value in concatenation (.) or string at App/Cpan.pm line 1158.
Could be reproduced calling, for example:

```
cpan -D PAR::Packer                               
CPAN: Storable loaded ok (v2.45)
Reading '/home/mudler/.cpan/Metadata'
  Database was generated on Sun, 11 May 2014 22:53:02 GMT
PAR::Packer
-------------------------------------------------------------------------
Use of uninitialized value in concatenation (.) or string at App/Cpan.pm line 1158.
        (no description)
        R/RS/RSCHUPP/PAR-Packer-1.017.tar.gz
        CPAN:      1.017  Not up to date
        Roderich Schupp (RSCHUPP)
        rschupp@cpan.org
```

The patch will change the output like that
```
CPAN: Storable loaded ok (v2.45)
Reading '/home/mudler/.cpan/Metadata'
  Database was generated on Sun, 11 May 2014 22:53:02 GMT
PAR::Packer
-------------------------------------------------------------------------
        (no description)
        R/RS/RSCHUPP/PAR-Packer-1.017.tar.gz
        (no installation file)
        Installed: not installed
        CPAN:      1.017  Not up to date
        Roderich Schupp (RSCHUPP)
        rschupp@cpan.org
```

Adding also the "not installed" information