[pycaffe] add converter for vectors of Nets
[pycaffe] expose SGDSolver.test_nets
add accessor for Solver::iter_

This will be useful in code controlling the solver (from pycaffe, for
example).
[pycaffe] expose SGDSolver.iter
Update detect.py

This generator causes an error in detect_windows because it is run twice there.
Better store it as a data structure instead.
Merge pull request #1198 from dbbert/patch-1
Back-merge to include #1198
add factory header to caffe hpp
Merge pull request #1196 from longjon/python-solver-improvements

Python solver improvements
Merge pull request #1208 from Yangqing/dev

add factory header to caffe hpp
Add caffe_*_add_scalar methods with different source/dest.
Add caffe_gpu_exp math function
Add ExpLayer to calculate y = base ^ (scale * x + shift)