BLD : change version from == -> >=

Changed == version checks to >= so that tomopy will build with
the dev versions with out trying to pull in code from pypi.
BLD : tweaked lboost_thread flag

changed flag from lboost_thread-mt -> lboost_thread.

It seems that the former is just a soft link to the later and ubuntu
does not package that soft link.

see:
https://stackoverflow.com/questions/3031768/boost-thread-linking-boost-thread-vs-boost-thread-mt