Render spreadsheets in eyeVisor

* This commit resolves the problem of spreadsheets (*.ods, *.xls) not being rendered in eyeVisor
* The problem is a legacy issue left over from the transition to unoconv
   - The old soffice route used the 'HTML (StarCalc)' format for spreadsheets and 'HTML (StarWriter)' for everything else.
   - Unoconv cannot understand these formats, and whilst 'HTML (StarWriter)' was picked up on and changed to 'html', 'HTML (StarCalc)' was not.
   - 'HTML (StarCalc)' has now been dropped in favour of 'html'

* As far as I know, this commit does not alter/affect the eyeSheets application in any way.
Update other instances of 'HTML (StarCalc)'

* Change to use 'html' directly
Merge pull request #26 from s0600204/officeAlt

Office : Spreadsheet display in eyeVisor (Take 2)