data: small fixes to csv mode
data: windows compatibility with csv module

in Py2 wants binary write
in Py3 wants newline=''
Merge pull request #333 from mrocklin/csv-fixes

Csv fixes
docs: update data descriptor.rst
docs: revamp index
update dependencies
docs: revamp overview
docs: correct column names in data
docs: remove name of file from csv content
docs: walk over index again
docs: simple install instructions with conda
docs: walk over overview again
docs: small edits to data_descriptor
docs: rename data, add current state
add expressions doc
add backends