BinariesServlet can hold to many jcr sessions open resulting in pool being exhausted

The binaries servlet streams binaries to a browser. A slow internet connection from a user can result in a jcr session being kept from the jcr pool for a long time. Suggested improvements

1) increase default jcr session pool max size from 25 --> 100
2) make pool size configurable
3) all or only large binaries should be first locally stored on filesystem, then the jcr session released, and then the response being streamed from filesystem to the browser.