BUG: Make ExcelFile.parse pass kwds to TextParser
BUG: (GH4145/4146) Fixed bugs in multi-index selection with column multi-index and duplicates
Merge pull request #4139 from jtratner/excel_fix

BUG: Make ExcelFile.parse pass kwds to TextParser
Merge pull request #4148 from jreback/mi2

BUG: (GH4145/4146) Fixed bugs in multi-index selection with column multi index duplicates
BLD: add requirements files

This commit adds 5 requirements files: one for each Travis build. The
corresponding sections in ci/install.sh are also removed in favor of these
files.

This allows pandas to have more fine-grained control over versions of
hard and soft deps when using travis.
CLN: do not depend on ordering of travis.yml
CLN: add explicit versions for everything
CLN: pass explicit path in ci/install.sh