Default project sharing level should be setable

[Jari Häkkinen]

Currently the sharing level is set but the setting used in the previous share event. It would be nice if the default sharing level can be set for a project. If no preset exists the current scheme should be used.

[Nicklas Nordborg]

It should be possible to add this as a property on the project. It should only require an 'int' column. Existing projects should get a value that corresponds to the current default (READ-USE-WRITE-DELETE).

This ticket can be sub-divided into three parts:

1. Add support in data-layer and the core to access/store this information. Don't forget to update UML diagram and docbook documentation (Data layer API).
2. Add support in the web interface to display/change this information. Don't forget to update user documentation.
3. Add changes to the core to use the information when auto-sharing new items.

[Nicklas Nordborg]

(In [4689]) References #1184: Default project sharing level should be setable

Step 1 and 3 is done.

[Nicklas Nordborg]

(In [4690]) Fixes #1184: Default project sharing level should be setable