v↑ ZODB5 stack

Let's pick up all fixes and improvements accumulated upstream to be used together with Zope4/Python2.

/reviewed-by @jerome, @levin.zimmermann
/reviewed-on !1332

component/ZEO/buildout.cfg

@@ -65,7 +65,7 @@ egg     = ZEO
 eggs    = ${:egg}
 
 egg-versions =
-  ZEO = 5.2.3
+  ZEO = 5.4.0
   trollius = 2.2.1
   futures = 3.3.0
 

component/ZODB/buildout.cfg

@@ -58,7 +58,7 @@ egg-versions =
 [ZODB5]
 <= _ZODB
 egg-versions =
-  ZODB = 5.6.0
+  ZODB = 5.8.0
   transaction = 2.4.0