Branching 0.15.X to prepare the 0.15.0b1 release

DOC: fix 2 covariance examples rst math markup.

Some formulas in plot_mahalanobis_distances and
plot_robust_vs_empirical_covariance were not correctly rendered by sphinx
as some characters were not properly escaped. This is fixed by setting the
docstrings as raw string using r"""

There was also missing braces for the number of features and samples subscript.

REL: Release 0.14.1

Minor bug fix release to restore proper behavior of setup.py

0.14 release

REL: 0.14a1 Release candidate for 0.14

REL increased version number, added whatsnew

website: fix for survey bar

DOC updated commit counts.

REL: 0.12.1 Bugfix release

Debian release 0.12.0-1