Clearing of contentcache

*Title: Clearing of contentcache

Incentive:
Make it easy to clear the viewcache for a given node or subtree without
resorting to clearing all the content cache.
This will help keep the load on a server down by only clear caches
that have new and updated templates ready.

*Documentation:
A new script was made for this called contentcache.sh which accepts
a list of node IDs/nice urls.

Clearing a given node is done with:
./bin/php/ezcontentcache.php --clear-node=/
or for multiple nodes (5 is users)
./bin/php/ezcontentcache.php --clear-node=/,5


Clearing a given subtree is done with:
./bin/php/ezcontentcache.php --clear-subtree=2
or for multiple subtrees
./bin/php/ezcontentcache.php --clear-subtree=2,users