Add more classifiers.

Classifiers added:
 - Decision Tree
 - Support Vector Machine
Modify mlpipe.py output.
Add generators and search spaces (not complete)

Added Space classes in order to make searching easier:
 - FixSpace
 - RemoveSpace
 - NormalizeSpace
 - QuantifySpace

Above classes utilize generators, which help in
creating various types of subsets, etc:
 - SubsetGenerator
 - MuliSubsetGenerator
 - DistributionGenerator