adds cancel buttons to the session
Implement error checking for non-deck voting
fixes bug that cancelled session is listed as open session
adds cancelled session branch to overview tree
adds number of sessions for each branch in the overview tree
adds table model in support for refreshing the tree
code refactoring
expand new session and open session branches
fix the bug that branches were not initially expanded.
Fix conflicts
limits to owner who can edit a sessoin.
moves vote panel buttons around and change the behavior
refactors codes and fixes codePro warnings
adds hashmap to remember tree expansion
restores tree to the previous expanded/closed states
Merge conflicts
Fixes save requirement button nakalamvokis
Fixes save changes to a requirement nakalamvokis
Fixes save changes to a requirement button nakalamvokis
Fixes save changes to a requirement button nakalamvokis