Bug 22278: Clear cache when creating new report groups or subgroups

Bug 22278: Clear cache when creating new report groups or subgroups

When a user adds a new group we create it, then fetch the groups from the cache. However, we aren't clearing the cache on creation. This patch fixes that

To test:
 0) Start a new report
 1) Pick create for the group
 2) Enter code and value
 3) Save
 4) You remain on the page and value and code are now empty (ok)
 5) BUT: The pull down for the group remains "None" instead of reflecting
    the new group
 6) Open a new tab and browse to reports - note the group exists and the report is in it
 7) On original tab save report again, the group was not selected so is lost
 8) Apply patch
 9) Retest with a new report
10) Group is created, saved, and selected upon save
11) Subsequent edits include the new group
12) Test with subgroups as well

Signed-off-by: Liz Rea <wizzyrea@gmail.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>