Add a "CSV for Excel" download link #1322

We regularly receive emails from users who claim the CSV export doesn't work well in Excel.

CSV with comma separated values doesn't import well in Excel 2007. It imports well in OpenOffice calc though.

It seems Excel by default only accepts tabs as delimiters. Piwik could add an export link in the table footers "CSV for Excel" which would be the CSV export, with a tab delimiter.

Wouldn't this be better described as "TSV - tab separated values" ?

(In [2131]) CSV renderer works with tab delimited values refs #1322

Vipsoft, maybe "TSV (Excel)" ? to make it clear that this works in excel, when CSV doesn't by default

(In [2181]) Fixes #1322 Adding CSV that works in Excel (TSV)