Enable gzip compression in Apache with mod_deflate

<IfModule mod_deflate.c>
    AddOutputFilterByType DEFLATE text/html text/plain text/css text/xml
    AddOutputFilterByType DEFLATE application/javascript application/x-javascript

    BrowserMatch ^Mozilla/4         gzip-only-text/html
    BrowserMatch ^Mozilla/4.0[678] no-gzip
    BrowserMatch bMSIEb           !no-gzip !gzip-only-text/html
</IfModule>