BUG:  (GH2702) Bug with Series indexing not raising an error when the right-hand-side has an incorrect length
CLN: Move print_versions into pandas proper.

CLN: Make print_versions export a method

Make ci/print_versions call pandas/util/print_versions
Merge pull request #4760 from jtratner/add-versions-method

CLN: Move print_versions into pandas proper.
Merge pull request #4756 from jreback/nested

BUG/ER:  (GH2702) Bug with Series indexing not raising an error when the right-hand-side has an incorrect length
ENH: Add 'add_metaclass' class decorator.

Taken from a new addition to the six library (again, license is in the
LICENSE directory).
CLN: Make ExcelWriter more pluggable

Make ExcelWriter an ABC and add ExcelWriter config to core/config_init