Stetho leaks sockets causing app crash on Android 4.4

[gmk57]

This is probably the same issue as #308 - which is closed, and it seems nobody's going to reopen it.
But it still exists in v1.5.1, 100% reproducible on emulator with an almost empty project.

Steps to reproduce:

1. Create AVD with any API 19 image (x86, x86 + Google APIs, ARM...)
2. Launch sample app
3. Open chrome://inspect/#devices in Chrome
4. After ~10 minutes Stetho reaches 1024 files/sockets and stops:

W/System.err: java.io.IOException: Too many open files
W/System.err:     at android.net.LocalSocketImpl.accept(Native Method)
W/System.err:     at android.net.LocalSocketImpl.accept(LocalSocketImpl.java:328)
W/System.err:     at android.net.LocalServerSocket.accept(LocalServerSocket.java:94)
W/System.err:     at com.facebook.stetho.server.LocalSocketServer.listenOnAddress(LocalSocketServer.java:85)
W/System.err:     at com.facebook.stetho.server.LocalSocketServer.run(LocalSocketServer.java:74)
W/System.err:     at com.facebook.stetho.server.ServerManager$1.run(ServerManager.java:40)
W/stetho: I/O error initialising connection thread
I/stetho: Server shutdown on @stetho_gmk57.teststetho_devtools_remote

5. After that, click on EditText in app. App crashes.