Merge pull request #3887 from jreback/loc_name

BUG: (GH3880) index names are now propogated with loc/ix
Merge pull request #3891 from jreback/hdf_bld

BLD: install older versions of numexpr/pytables on fulldeps/2 build
DOC: minor io.rst edits
TST: json tests to int64 to avoid dtype issues
TST: skip tests if xlrd has lower than needed version
TST: skip pickle tests on not-little endianess
TST: skip test_encoding on non-little endian in test_pytables
TST: skip some stata tests on non-little endian
TST: convered skips on knownfailures to knownfailures (test_pickle/test_stata)