Fixes import references for run_all_classifiers

[mloning]

What does this implement/fix? Explain your changes.
Fixes references for MaxEntBatch and MaxEntOnline. Previously, threw error as classes were not found.

Other comments
I also suggest to clean up the imports using the following code instead of changing the path, happy to make changes to this PR if you like:

from lxmls.classifiers import naive_bayes as nbc
from lxmls.classifiers import perceptron as percc
from lxmls.classifiers import svm as svmc
from lxmls.classifiers import mira as mirac
from lxmls.classifiers import max_ent_batch as mec_batch
from lxmls.classifiers import max_ent_online as mec_online