Add IRC channel name to iCal meeting summary

Previously, generated iCal events for OpenStack meetings that met at
different times were made unique by incrementing a number and
appending that number to the iCal event summary field.

iCal event uniqueness is now assured by appending the IRC channel
room to the iCal event summary field instead.

Change-Id: I8bd77550a3e75714ae7ed35d07033d4b0f8ef367
Merge "Add IRC channel name to iCal meeting summary"