vchoi_fork

[svn-r14445] Added code to detect the situation in which a metadata cache entry flush
callback functions modifies the skip list or LRU out from under a partial
or complete flush of the cache.  This is a test for a situation that 
should not occur, but we test anyway.

Also added code to skip longer tests in cache_api in express tests.

Tested serial and parallel on phoenix (debian --x86-32), and commit test.

Elena commit tested as well, and ran a manual test under MacOS X.