grep IP at the start of lines

I'm not sure if this regex works best, so I'm patching this single file as a sample.

Don't forget to update `mail-whois-lines.conf` after this patch got merged.

For the following logs, `grep '[^0-9]199.48.161.87[^0-9]'` will output nothing, while `grep '\([^0-9]\|^\)199.48.161.87[^0-9]'` works:
<pre>199.48.161.87 - - [09/Sep/2014:13:38:54 +0800] "POST /wp-login.php HTTP/1.1" 403 4674 "-" "Mozilla/5.0 (Windows NT 6.1; rv:5.0) Gecko/20100101 Firefox/5.0" - hitsjapan.com
199.48.161.87 - - [09/Sep/2014:13:38:56 +0800] "POST /wp-login.php HTTP/1.1" 403 4674 "-" "Mozilla/5.0 (Windows NT 6.1; rv:5.0) Gecko/20100101 Firefox/5.0" - hitsjapan.com
199.48.161.87 - - [09/Sep/2014:13:38:58 +0800] "POST /wp-login.php HTTP/1.1" 403 4674 "-" "Mozilla/5.0 (Windows NT 6.1; rv:5.0) Gecko/20100101 Firefox/5.0" - hitsjapan.com
199.48.161.87 - - [09/Sep/2014:13:39:00 +0800] "POST /wp-login.php HTTP/1.1" 403 4674 "-" "Mozilla/5.0 (Windows NT 6.1; rv:5.0) Gecko/20100101 Firefox/5.0" - hitsjapan.com
199.48.161.87 - - [09/Sep/2014:13:39:05 +0800] "POST /wp-login.php HTTP/1.1" 403 4674 "-" "Mozilla/5.0 (Windows NT 6.1; rv:5.0) Gecko/20100101 Firefox/5.0" - hitsjapan.com
199.48.161.87 - - [09/Sep/2014:13:39:05 +0800] "POST /wp-login.php HTTP/1.1" 403 4674 "-" "Mozilla/5.0 (Windows NT 6.1; rv:5.0) Gecko/20100101 Firefox/5.0" - hitsjapan.com
199.48.161.87 - - [09/Sep/2014:13:39:13 +0800] "POST /wp-login.php HTTP/1.1" 403 4674 "-" "Mozilla/5.0 (Windows NT 6.1; rv:5.0) Gecko/20100101 Firefox/5.0" - hitsjapan.com
199.48.161.87 - - [09/Sep/2014:13:39:21 +0800] "POST /wp-login.php HTTP/1.1" 403 4674 "-" "Mozilla/5.0 (Windows NT 6.1; rv:5.0) Gecko/20100101 Firefox/5.0" - hitsjapan.com
199.48.161.87 - - [09/Sep/2014:13:39:32 +0800] "POST /wp-login.php HTTP/1.1" 403 4674 "-" "Mozilla/5.0 (Windows NT 6.1; rv:5.0) Gecko/20100101 Firefox/5.0" - hitsjapan.com
199.48.161.87 - - [09/Sep/2014:13:39:34 +0800] "POST /wp-login.php HTTP/1.1" 403 4674 "-" "Mozilla/5.0 (Windows NT 6.1; rv:5.0) Gecko/20100101 Firefox/5.0" - hitsjapan.com
199.48.161.87 - - [09/Sep/2014:13:39:34 +0800] "POST /wp-login.php HTTP/1.1" 403 168 "-" "Mozilla/5.0 (Windows NT 6.1; rv:5.0) Gecko/20100101 Firefox/5.0" - hitsjapan.com
199.48.161.87 - - [09/Sep/2014:13:39:34 +0800] "POST /wp-login.php HTTP/1.1" 403 168 "-" "Mozilla/5.0 (Windows NT 6.1; rv:5.0) Gecko/20100101 Firefox/5.0" - hitsjapan.com
199.48.161.87 - - [09/Sep/2014:13:39:35 +0800] "POST /wp-login.php HTTP/1.1" 403 168 "-" "Mozilla/5.0 (Windows NT 6.1; rv:5.0) Gecko/20100101 Firefox/5.0" - hitsjapan.com
199.48.161.87 - - [09/Sep/2014:13:39:35 +0800] "POST /wp-login.php HTTP/1.1" 403 168 "-" "Mozilla/5.0 (Windows NT 6.1; rv:5.0) Gecko/20100101 Firefox/5.0" - hitsjapan.com
199.48.161.87 - - [09/Sep/2014:13:39:35 +0800] "POST /wp-login.php HTTP/1.1" 403 168 "-" "Mozilla/5.0 (Windows NT 6.1; rv:5.0) Gecko/20100101 Firefox/5.0" - hitsjapan.com</pre>