Add, Remove, Replace functionality and other modifications

[senseisimple]

This patch includes some changes to the argument handling and validation routines.

The add and replace now accept stdin in order to allow for scripted usage such as dynamically feeding in config data, i.e.

apache-config replace site example.com <<'EOF'
<VirtualHost *:443>
        Protocols h2 http/1.1

        ServerName example.com
        DocumentRoot /var/www/vhosts/example.com/web
        <Directory /var/www/vhosts/example.com/web>
                AllowOverride All
                Options -Indexes
        </Directory>
        SSLEngine On
        SSLCertificateFile /etc/pki/tls/certs/__.crt
        SSLCertificateKeyFile /etc/pki/tls/private/__.key
        SSLCertificateChainFile /etc/pki/tls/certs/__.ca
</VirtualHost>
EOF