Initial support for weighted samples in svm module.

examples/svm/plot_weighted_samples.py

scikits/learn/linear_model/logistic.py

scikits/learn/linear_model/sparse/logistic.py

scikits/learn/svm/base.py

scikits/learn/svm/libsvm.py

scikits/learn/svm/setup.py

scikits/learn/svm/sparse/base.py

scikits/learn/svm/sparse/libsvm.py

scikits/learn/svm/src/libsvm/_libsvm.c

scikits/learn/svm/src/libsvm/_libsvm.pyx

scikits/learn/svm/src/libsvm/_libsvm_sparse.c

scikits/learn/svm/src/libsvm/_libsvm_sparse.pyx

scikits/learn/svm/src/libsvm/libsvm_helper.c

scikits/learn/svm/src/libsvm/libsvm_sparse_helper.c

scikits/learn/svm/src/libsvm/svm.cpp

scikits/learn/svm/src/libsvm/svm.h

scikits/learn/svm/tests/test_sparse.py

scikits/learn/svm/tests/test_svm.py