Fix bug with null pointer exception.

Steps to reproduce said bug:
1) Create 2 sessions: a and b
2) Add requirements to a
3) Activate session a
4) Vote on requirements on a
5) End session a
6) Open session b

Expected behavior: b opens
Actual behavior: null pointer exception

Null pointer exception was caused by a for loop that removed
session ID 1 from the stash. This was replaced with a simple
skip condition in the loop that populates the table model.