[client] Update default value to be of the right type.
[client] Update default value to be of the right type.

In optparse, if you use type='float', default=0, the default value type will be
int. That's cute.

Bug: 781021
Change-Id: Iab9a7b16486c311bdf5cf2241c4963c1447aa2b2
Reviewed-on: https://chromium-review.googlesource.com/1022375
Reviewed-by: Vadim Shtayura <9f116ddb1b24f6fc1916a676eb17161b6c07dfc1@chromium.org>
Commit-Queue: Marc-Antoine Ruel <d2bf0fc09b08f7b0888b3ddab32b3e89c7122c8b@chromium.org>

luci/luci-py,luci/luci-py,luci/luci-py,luci/luci-py