Fix false success in AssertCsv test
Reorganize files, fix pep8 lint, add comments
Drop create_csv from API

It's not clear what the use of this function is. Let the caller create the file.
Add support for modifying column headers

fixes #15 on github
fixes #17 on github

By default, verbose_name attributes on fields will be used for column headers, unless use_verbose_names is set to False.

Also, the user can provide a map, field_header_map, that will map field names to custom column headers. This will take precedence over verbose names, and can be used in conjunction with use_verbose_names=False.
Merge pull request #21 from steventlamb/topic/override_column_headers

Topic/override column headers
Improve test coverage

Don't test initialization code because it isn't relevant possible to trigger this in the test environment.

Test empty querysets.
test if this fixes the build.
take 2