Remove obsolete command line flags

This CL removes following command line flags from converter as those flags are no longer used.
--disable_lattice_cache
--disable_predictive_realtime_conversion

This is just a clean-up CL.  Hence no behavior change is intended.

Patch From Noriyuki Takahashi.

BUG=none
TEST=unittest


git-svn-id: http://mozc.googlecode.com/svn/trunk@550 a6090854-d499-a067-5803-1114d4e51264