when we right click on a contact that is not in the roster, there is 'add to roster' in the menu (fix ticket #55)

it can be configured through the advanced config window
fix ticket #184

to check_for_new_version

last time I see that before I block this kind of commit directly by svn.

the position of the button is probably not the final position.
modify config to support boolean value embedded in string because the treestore
store/edit all value with a string.

revert all new glade (2.6.10?) properties.