updated ostrich to 1.7.2-beta

experimental upgrade to commons pool 2.2
The builder now has 2 properties that configure the same thing. Potentially, you could set them to incompatible values resulting in undefined behavior. The other issue is that only WAIT is really supported, the other two options are not valid or supported anymore.

There are a couple of options:
1. Remove the cache exhaustion action
2. Reject the actions no longer supported (IllegalArgumentException) and have withCacheExhaustionAction set _blockWhenExhausted

I favor 1 since WAIT is the only supported action now