Bug in CLF model

[aphearin]

The cacciato09 model raises an exception when passed a non-integer value of the luminosity threshold. Here is a minimal reproducer:

from halotools.sim_manager import CachedHaloCatalog
from halotools.empirical_models import PrebuiltHodModelFactory

halocat = CachedHaloCatalog(simname='bolplanck')
halocat.halo_table['halo_m180b'] = halocat.halo_table['halo_mvir']

model = PrebuiltHodModelFactory('cacciato09', threshold=10.25)
model.populate_mock(halocat)

If threshold is set to either 10 or 11, no exception is raised.

[aphearin]

Not sure what was causing this issue but I cannot reproduce with the latest version of the code.