POC: Checkrestart performance improvements

This is a proof of concept to remove the requirement of `lsof` from `checkrestart`

`lsof` can take a long time to return on systems with a large number of files causing `checkrestart` to to take minutes to run. `lsof` also appears to use lots of CPU resources on systems with a large number of open files:

    # time checkrestart -p
    Found 1 processes using old versions of upgraded files
    (1 distinct program)
    (1 distinct packages) 
    These processes do not seem to have an associated init script to restart them:
    ruby1.9.1:
            8408    /usr/bin/ruby1.9.1
    
    real    1m3.366s
    user    0m33.206s
    sys     0m31.298s```

By utilising `/proc/<pid>/fd` to find open files natively in python and `pmap` to find mmap'd files in processes we can significantly reduce the processing time:

    # time /home/luser/checkrestart -p
    Found 1 processes using old versions of upgraded files
    (1 distinct program)
    (1 distinct packages)
    These processes do not seem to have an associated init script to restart them:
    ruby1.9.1:
            8408    /usr/bin/ruby1.9.1
    
    real    0m0.463s
    user    0m0.136s
    sys     0m0.144s```

I've also added an option to ignore specific pids during the check. Our MySQL servers have a ton of open files and we can reduce processing by ignoring the mysql daemon completely:

```/home/luser/checkrestart -p -e`cat /var/run/mysqld/mysqld.pid` ```