The San Jose webpagetest server went away, so replace it by LA.

We should probably rethink these entirely, but for now I've kept the
IE8 and IE9 servers, with no IE10 or IE11.  The one change I *did*
make was move london to IE9, since I think we get a lot more IE9 these
days than IE8.

Auditors: chris

Test Plan:
Fingers crossed