mask array gets reversed too
(copy and paste) documents "mask" kw in heatmap
heatmap: handles pandas and numpy masks
heatmap: narrows down exception type
Merge branch 'heatmap-missing-fixes' of github.com:sdvillal/seaborn into sdvillal-heatmap-missing-fixes
Add test and release notes for heatmap mask fix
Fix mask test on pandas 0.12
Attempt to make multilevel bootstrap test more robust