Accounts bloom (#2357)

* proper bloom

* incremental bloom updates

* crate update

* return of the column

* fix n^2 byteorder write

* add notes to funs

* working bloom commits

* Optimizations

* bloom diag

* migration basic

* migration ongoing

* migration finalizing

* mingration api workarounds

* fix test_client setups

* snapshot bloom update

* review fixes

* just forward keys in the migration

* migration extra tracing

* fix migration path

* remove close pray

* review issues

util/src/migration/mod.rs

@@ -102,6 +102,12 @@ impl From<::std::io::Error> for Error {
 	}
 }
 
+impl From<String> for Error {
+	fn from(e: String) -> Self {
+		Error::Custom(e)
+	}
+}
+
 /// A generalized migration from the given db to a destination db.
 pub trait Migration: 'static {
 	/// Number of columns in database after the migration.