Update unoconv submodule

- To reflect changes in Dag Wieers' master
- Also, change checks for unoconv from read/write to read/execute
Alter checks for unoconv

- We pass unoconv as an argument to python which executes it for us.
- Therefore we don't need to check that if unoconv is directly executable.
De-hardcoding calendar colours

The colours for the Calendar widget are, for some reason, set via JS rather than CSS
* Admittedly, these colours can be altered - but on application start via arguments passed from php and set by the application using the widget.
* But this leads to the possibility of a user's selected theme conflicting with the colours chosen by an application developer.
This commit permits theme developers to colour the calendar widget along with the rest of the ui via CSS Stylesheets.
Merge pull request #27 from s0600204/office

Update unoconv submodule
Remove code accidentally left behind from an experimental line of development
Merge pull request #29 from s0600204/minical

De-hardcoding calendar colours