make maximum threads configurable

[kortemik]

rlo_12/src/main/java/com/teragrep/rlo_12/FileStatusManager.java

Line 49 in 0a2e2b0

this.threadPoolExecutor = new ThreadPoolExecutor(1, 8, 60, TimeUnit.SECONDS, new LinkedBlockingQueue<>());

currently configures to 1 min 8 max