Blazeutils

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- Added Python 3.5 compatibility
- Set up CI and coverage

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- Fixed spreadsheets.xlsx_to_reader Python 3.4 compatibility
- Fixed numbers.convert_int exception test for Python 3.4 compatibility
- Fixed case where error handling's _uie_matches masked real exception by creating one

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- Added Python 3.4 compatibility.
- Remove blazeutils.xlrd. It had been deprecated and the objects moved to .spreadsheets.

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- changed how the version string is determined in __init__.py
- archive old changelog notes

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- add xlsx_to_strio() and WriterX.mwrite()

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- fix wrong dates for 0.4.0 and 0.4.1 releases in changelog
- add roundsecs argument to dates.trim_mils
- updates to spreadsheets module including .xlsx file support

- xlsx_to_reader(): converts xlsxwriter.Workbook instance to xlrd reader
- WriterX: like Writer but for xlsxwriter Worksheets, API is slightly different and won't have
any faculties for style management like Writer does.
- Reader: gets a .from_xlsx() method
- http_headers(): utility function to help when sending files as HTTP response