API Change repr name for table schema
Not API breaking, since pandas 0.20.0 hasn't been released yet.
`_repr_table_schema_` isn't the right name, since we include both the schema and the data.

xref https://github.com/pandas-dev/pandas/pull/16198#discussion_r114342141

@rgbkrk do you need any kind of backwards compatibility with `_repr_table_schema_`?