Update advertiser-index.php

The $banner variable in the foreach reference loop must be unset to avoid an active advertiser appearing inactive when the $banner variable is used for building the advertiser tree. 

See the warning on http://php.net/manual/en/control-structures.foreach.php :
"Reference of a $value and the last array element remain even after the foreach loop. It is recommended to destroy it by unset()."
Merge pull request #237 from mreiden/master

Fix #232
Fix #241 - Typo in the recent SWF fix
Regenerated delivery scripts - Ref #241
Updated release notes Ref #241
Regenerated plugins

Commits:
 * Regenerated delivery scripts - Ref #241
 * Updated release notes Ref #241
Initial support for Webm video ads
Bumped version to 1.10.0
Rebuilt plugin
Ref #255 - Updated release notes
Merge pull request #255 from revive-adserver/webm-support

Added support for WebM videos in the IAB Video plugin
Fixed #260
Fixed #261
Cleaned up unused files
Merge branch 'master' into 231_greater_midnight_sync_delay

Conflicts:
	RELEASE_NOTES.txt