COSMIT refactor LibSVM wrapper for safety and readability

* don't pass fit-time parameters to prediction functions
* do memory deallocation in a finally clause
* trim docstrings and comments

TODO:
* fit needs the finally clause as well
* sparse LibSVM should get the same treatment

(test_svc_clone_with_callable_kernel might fail sometimes. That appears
to be unrelated.)
DOC fix some broken URLs
PY3: New test for the get_params handling of deprecated attributes.

This test passes under Python 2.7 but currently fails under Python
3.2+. This change of behavior makes many doctest fail under Python 3
while they pass under Python 2.

The goal of this test is to help find the cause of the issue under
Python 3 and also act as a non regression test once a fix is found
under Python 3.
DOC: Clarify docs on preprocessing.Binarizer.

- Values below the threshold also remain 0
- Values are replaced by integer 1 not floating point 1.0

Some changes by @larsmans. Fixes #2066.
merging upstream master
Couple small changes from code review.