fix: l1_ratio is incorrect; its (1.0 - rho); added test case to make sure elastic net penalty with l1_ratio near to 1 and 0 matches L1 and L2 penalties.
added change log entry
set l1_ratio to (1.0 - l1_ratio)
revert: reverted l1_ratio change - not SGDRegressor - sorry
Merge pull request #2631 from pprett/fix-sgd-l1-ratio

[MRG] Fix sgd l1 ratio