[web/test] don't delete uicache directory
Other tests use it, so the rmtree was a bit too much. Set CACHEDIR to a
temporary subdirectory, and only delete that.
HTTP cache management
=====================
.. automodule:: cubicweb.web.httpcache
Cache policies
--------------
.. autoclass:: cubicweb.web.httpcache.NoHTTPCacheManager
.. autoclass:: cubicweb.web.httpcache.MaxAgeHTTPCacheManager
.. autoclass:: cubicweb.web.httpcache.EtagHTTPCacheManager
.. autoclass:: cubicweb.web.httpcache.EntityHTTPCacheManager
Exception
---------
.. autoexception:: cubicweb.web.httpcache.NoEtag
Helper functions
----------------
.. autofunction:: cubicweb.web.httpcache.set_http_cache_headers
.. NOT YET AVAILABLE IN STABLE autofunction:: cubicweb.web.httpcache.lastmodified