[CHG]account_financial_report_webkit_xls: Migration to v8
[CHG]account_financial_report_webkit_xls: Migration to v8
[FIX]account_financial_report_webkit_xls: pep8 + travis
[FIX]account_financial_report_webkit_xls: pep8
[CHG] travis.yml

Use the official branch 8.0 since https://github.com/OCA/reporting-engine/pull/5 has been merged.
Merge pull request #23 from acsone/8.0-account_financial_report_webkit_xls

account_financial_report_webkit_xls: Port to 8.0