Polishing Actually enable fat db pr (#1974) (#2048)

* Actually enable fat db, and do RPCs for it.

* Implement HashDB traits for AccountDB.

* user defaults

* finished user defaults

* user defaults are network-dependent

* added tests for newly added functions, logger is initialized first

* dir cleanup in progress

* user_file is placed next to snapshots

* fixing requested change

util/src/trie/mod.rs

@@ -233,4 +233,7 @@ impl TrieFactory {
 			TrieSpec::Fat => Ok(Box::new(try!(FatDBMut::from_existing(db, root)))),
 		}
 	}
+
+	/// Returns true iff the trie DB is a fat DB (allows enumeration of keys).
+	pub fn is_fat(&self) -> bool { self.spec == TrieSpec::Fat } 
 }