mctest.php: nicely align server names
The servers entries being made of an IP address and a port, they would
often have different lenghts which clutter the output indentation.
Previously the output columns would be slightly misaligned:
$ mwscript mctest.php --wiki=enwiki
10.4.1.255:11211 set: 100 time: 0.
17192602157593
10.4.1.1:11211 set: 100 time: 0.
19056081771851
$
With this patch:
$ mwscript mctest.php --wiki=enwiki
10.4.1.255:11211 set: 100 time: 0.
17192602157593
10.4.1.1:11211 set: 100 time: 0.
19056081771851
$
Change-Id: I80199a229ed6310686411f08e0344c7d906414ea